diff --git a/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/main/java/org/activiti/api/runtime/model/impl/StringToDateConverter.java b/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/main/java/org/activiti/api/runtime/model/impl/StringToDateConverter.java
index b1d263181cf0b54be133ae0d514740e462fdecf2..9c7d715ba31f6479cab3dcb9d8c2bee992709f60 100644
--- a/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/main/java/org/activiti/api/runtime/model/impl/StringToDateConverter.java
+++ b/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/main/java/org/activiti/api/runtime/model/impl/StringToDateConverter.java
@@ -17,7 +17,10 @@ package org.activiti.api.runtime.model.impl;
 
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
+import java.time.Instant;
+import java.time.OffsetDateTime;
 import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
 import java.util.Date;
 import java.util.TimeZone;
 
@@ -26,18 +29,12 @@ import org.springframework.core.convert.converter.Converter;
 @ProcessVariableTypeConverter
 public class StringToDateConverter implements Converter<String, Date> {
 
-    private static SimpleDateFormat ISO_DATE_TIME = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
-
-    static {
-      ISO_DATE_TIME.setTimeZone(TimeZone.getTimeZone("UTC"));
-    }
-
     @Override
     public Date convert(String source) {
-        try {
-            return ISO_DATE_TIME.parse(source);
-        } catch (ParseException e) {
-            throw new RuntimeException(e);
+        if (source.endsWith("Z")) {
+            return Date.from(Instant.parse(source));
+        } else {
+            return Date.from(OffsetDateTime.parse(source).toInstant());
         }
     }
 }
diff --git a/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/test/java/org/activiti/api/runtime/model/impl/StringToDateConverterTest.java b/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/test/java/org/activiti/api/runtime/model/impl/StringToDateConverterTest.java
index 2973bb084f3d4950a191c395497f24c575268bee..72bec28c56184bf64b0fa6cba6f24d43aa4e7d4f 100644
--- a/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/test/java/org/activiti/api/runtime/model/impl/StringToDateConverterTest.java
+++ b/activiti-core/activiti-api-impl/activiti-api-process-model-impl/src/test/java/org/activiti/api/runtime/model/impl/StringToDateConverterTest.java
@@ -17,38 +17,39 @@
 package org.activiti.api.runtime.model.impl;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 
 import java.time.Instant;
 import java.util.Date;
+import java.util.stream.Stream;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 class StringToDateConverterTest {
 
-    private StringToDateConverter subject = new StringToDateConverter();
-
-    @Test
-    void convertISODateTimeUTC() {
-        //given
-        String source = "2022-01-17T00:00:00.000Z";
+    private static Instant example = Instant.parse("2022-01-17T00:00:00Z");
 
-        //when
-        Date result = subject.convert(source);
-
-        //then
-        assertThat(result).isEqualTo(Instant.parse(source));
+    private static Stream<Arguments> arguments() {
+        return Stream.of(
+            Arguments.of("2022-01-17T00:00:00.000Z", example),
+            Arguments.of("2022-01-17T00:00:00Z", example),
+            Arguments.of("2022-01-17T00:00:00.000-00:00", example),
+            Arguments.of("2022-01-17T00:00:00-00:00", example)
+        );
     }
 
-    @Test
-    void convertISODateTimeOffset() {
-        //given
-        String source = "2022-01-17T00:00:00.000-00:00";
+    private StringToDateConverter subject = new StringToDateConverter();
 
+    @ParameterizedTest
+    @MethodSource("arguments")
+    public void convert(String source, Instant expected) {
         //when
         Date result = subject.convert(source);
 
         //then
-        assertThat(result).isEqualTo(Date.from(Instant.parse("2022-01-17T00:00:00.000Z")));
+        assertThat(result.toInstant()).isEqualTo(expected);
     }
 
 }