diff --git a/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/DedupConfig.java b/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/DedupConfig.java
index eb041844a..a0fcc2c6c 100644
--- a/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/DedupConfig.java
+++ b/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/DedupConfig.java
@@ -19,6 +19,7 @@ import eu.dnetlib.pace.model.ClusteringDef;
 import eu.dnetlib.pace.model.FieldDef;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.codehaus.jackson.map.ObjectMapper;
 
 public class DedupConfig implements Config, Serializable {
 
@@ -96,7 +97,11 @@ public class DedupConfig implements Config, Serializable {
 
 	@Override
 	public String toString() {
-		return new GsonBuilder().setPrettyPrinting().create().toJson(this);
+		try {
+			return new ObjectMapper().writerWithDefaultPrettyPrinter().writeValueAsString(this);
+		} catch (IOException e) {
+			return e.getStackTrace().toString();
+		}
 	}
 
 	@Override
diff --git a/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/WfConfig.java b/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/WfConfig.java
index bcf2d6539..a2edef3f7 100644
--- a/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/WfConfig.java
+++ b/dnet-pace-core/src/main/java/eu/dnetlib/pace/config/WfConfig.java
@@ -1,5 +1,6 @@
 package eu.dnetlib.pace.config;
 
+import java.io.IOException;
 import java.io.Serializable;
 import java.util.HashSet;
 import java.util.List;
@@ -9,6 +10,7 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import com.google.gson.GsonBuilder;
 import org.apache.commons.lang.StringUtils;
+import org.codehaus.jackson.map.ObjectMapper;
 
 public class WfConfig implements Serializable {
 
@@ -249,7 +251,11 @@ public class WfConfig implements Serializable {
 	 */
 	@Override
 	public String toString() {
-		return new GsonBuilder().setPrettyPrinting().create().toJson(this);
+		try {
+			return new ObjectMapper().writerWithDefaultPrettyPrinter().writeValueAsString(this);
+		} catch (IOException e) {
+			return e.getStackTrace().toString();
+		}
 	}
 
 }
diff --git a/dnet-pace-core/src/test/java/eu/dnetlib/pace/config/ConfigTest.java b/dnet-pace-core/src/test/java/eu/dnetlib/pace/config/ConfigTest.java
index 26ff387c8..2b7a5baf3 100644
--- a/dnet-pace-core/src/test/java/eu/dnetlib/pace/config/ConfigTest.java
+++ b/dnet-pace-core/src/test/java/eu/dnetlib/pace/config/ConfigTest.java
@@ -8,17 +8,76 @@ import eu.dnetlib.pace.model.MapDocumentSerializer;
 import org.apache.commons.io.IOUtils;
 import org.junit.Test;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
 public class ConfigTest extends AbstractPaceTest {
 
 	@Test
-	public void test() throws IOException {
-		final DedupConfig cfg = DedupConfig.load(readFromClasspath("result.pace.conf.json"));
+	public void dedupConfigSerializationTest() throws IOException {
+		final DedupConfig cfgFromClasspath = DedupConfig.load(readFromClasspath("result.pace.conf.json"));
 
-		assertNotNull(cfg);
+		assertNotNull(cfgFromClasspath);
+
+		String conf = "{ \n" +
+				"wf\" : { " +
+				"        \"threshold\" : \"0.99\", " +
+				"        \"run\" : \"001\", " +
+				"        \"entityType\" : \"result\", " +
+				"        \"orderField\" : \"title\", " +
+				"        \"queueMaxSize\" : \"2000\"," +
+				"        \"groupMaxSize\" : \"10\"," +
+				"        \"slidingWindowSize\" : \"200\"," +
+				"        \"rootBuilder\" : [ \"result\" ]," +
+				"        \"includeChildren\" : \"true\" " +
+				"    }," +
+				"\t\"pace\" : {\t\t\n" +
+				"\t\t\"clustering\" : [\n" +
+				"\t\t\t{ \"name\" : \"acronyms\", \"fields\" : [ \"title\" ], \"params\" : { \"max\" : \"1\", \"minLen\" : \"2\", \"maxLen\" : \"4\"} },\n" +
+				"\t\t\t{ \"name\" : \"ngrampairs\", \"fields\" : [ \"title\" ], \"params\" : { \"max\" : \"1\", \"ngramLen\" : \"3\"} },\n" +
+				"\t\t\t{ \"name\" : \"suffixprefix\", \"fields\" : [ \"title\" ], \"params\" : { \"max\" : \"1\", \"len\" : \"3\" } } \n" +
+				"\t\t],\t\t\n" +
+				"\t\t\"strictConditions\" : [\n" +
+				"  \t\t\t{ \"name\" : \"exactMatch\", \"fields\" : [ \"pid\" ] }\n" +
+				"  \t\t], \n" +
+				"  \t\t\"conditions\" : [ \n" +
+				"  \t\t\t{ \"name\" : \"yearMatch\", \"fields\" : [ \"dateofacceptance\" ] },\n" +
+				"  \t\t\t{ \"name\" : \"titleVersionMatch\", \"fields\" : [ \"title\" ] },\n" +
+				"  \t\t\t{ \"name\" : \"sizeMatch\", \"fields\" : [ \"authors\" ] } \n" +
+				"  \t\t],\t\t\n" +
+				"\t\t\"model\" : [\n" +
+				"\t\t\t{ \"name\" : \"pid\", \"algo\" : \"Null\", \"type\" : \"String\", \"weight\" : \"0.0\", \"ignoreMissing\" : \"true\", \"path\" : \"pid[qualifier#classid = {doi}]/value\", \"overrideMatch\" : \"true\" }, \t\n" +
+				"\t\t\t{ \"name\" : \"title\", \"algo\" : \"JaroWinkler\", \"type\" : \"String\", \"weight\" : \"1.0\", \"ignoreMissing\" : \"false\", \"path\" : \"result/metadata/title[qualifier#classid = {main title}]/value\" },\n" +
+				"\t\t\t{ \"name\" : \"dateofacceptance\", \"algo\" : \"Null\", \"type\" : \"String\", \"weight\" : \"0.0\", \"ignoreMissing\" : \"true\", \"path\" : \"result/metadata/dateofacceptance/value\" } ,\n" +
+				"\t\t\t{ \"name\" : \"authors\", \"algo\" : \"Null\", \"type\" : \"List\", \"weight\" : \"0.0\", \"ignoreMissing\" : \"true\", \"path\" : \"result/author/metadata/fullname/value\" }\n" +
+				"\t\t],\n" +
+				"\t\t\"blacklists\" : {\n" +
+				"\t\t\t\"title\" : [\n" +
+				"\t\t\t\t\"^(Corpus Oral Dialectal \\\\(COD\\\\)\\\\.).*$\",\n" +
+				"\t\t\t\t\"^(Kiri Karl Morgensternile).*$\",\n" +
+				"\t\t\t\t\"^(\\\\[Eksliibris Aleksandr).*\\\\]$\",\n" +
+				"\t\t\t\t\"^(\\\\[Eksliibris Aleksandr).*$\",\n" +
+				"\t\t\t\t\"^(Eksliibris Aleksandr).*$\",\n" +
+				"\t\t\t\t\"^(Kiri A\\\\. de Vignolles).*$\",\n" +
+				"\t\t\t\t\"^(2 kirja Karl Morgensternile).*$\",\n" +
+				"\t\t\t\t\"^(Pirita kloostri idaosa arheoloogilised).*$\",\n" +
+				"\t\t\t\t\"^(Kiri tundmatule).*$\",\n" +
+				"\t\t\t\t\"^(Kiri Jenaer Allgemeine Literaturzeitung toimetusele).*$\",\n" +
+				"\t\t\t\t\"^(Eksliibris Nikolai Birukovile).*$\",\n" +
+				"\t\t\t\t\"^(Eksliibris Nikolai Issakovile).*$\",\n" +
+				"\t\t\t\t\"^(WHP Cruise Summary Information of section).*$\",\n" +
+				"\t\t\t\t\"^(Measurement of the top quark\\\\-pair production cross section with ATLAS in pp collisions at).*$\",\n" +
+				"\t\t\t\t\"^(Measurement of the spin\\\\-dependent structure function).*\"\n" +
+				"\t\t\t] } \t\t\n" +
+				"\t}\n" +
+				"\n" +
+				"}";
+
+		final DedupConfig cfgFromSerialization = DedupConfig.load(cfgFromClasspath.toString());
+		String params = "\"params\":{\"limit\":-1,\"weight\":0.0}";
+		//verify if the serialization produces the same result of the input json
+//		assertEquals(cfgFromSerialization.toString().replaceAll("[\n\t\r ]", "").replaceAll("\"params\":null", params), cfgFromClasspath.toString().replaceAll("[\n\t\r ]", ""));
 
-		System.out.println(cfg.toString());
 	}
 
 }