diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 6e9a7039d..db3afea3d 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -246,7 +246,7 @@ if( ENABLE_EXTRA_TESTS AND HAVE_ECCODES_THREADS )
                       COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/grib_encode_pthreads.sh
     )
 
-    foreach( test grib_ecc-604 bufr_ecc-604 )
+    foreach( test grib_ecc-604 grib_ecc-604-encode bufr_ecc-604 )
         ecbuild_add_executable( TARGET    ${test}
                                 NOINSTALL
                                 SOURCES   ${test}.c
diff --git a/tests/grib_ecc-604-encode.c b/tests/grib_ecc-604-encode.c
new file mode 100644
index 000000000..82e245457
--- /dev/null
+++ b/tests/grib_ecc-604-encode.c
@@ -0,0 +1,145 @@
+/*
+ * Test for ECC-604: GRIB decoding/encoding sequentially and parallel with POSIX threads
+ */
+#include <time.h>
+#include <pthread.h>
+#include <assert.h>
+#include <unistd.h>
+
+#include "grib_api.h"
+
+/* These are passed in via argv */
+static size_t NUM_THREADS         = 0;
+static size_t FILES_PER_ITERATION = 0;
+static char*  INPUT_FILE          = NULL;
+int opt_dump  = 0; /* If 1 then dump handle to /dev/null */
+int opt_clone = 0; /* If 1 then clone source handle */
+int opt_write = 0; /* If 1 write handle to file */
+
+static int encode_values(grib_handle* h, char *output_file)
+{
+    double *values;
+    size_t size = 1000 * 1000;
+    size_t i = 0;
+    values = (double*)malloc(size*sizeof(double));
+    for (i=0; i<size; ++i) {
+        double v = i;
+        if (i % 1000 == 0) v = 0;
+        values[i] = v;
+    }
+    GRIB_CHECK(grib_set_long(h,"bitsPerValue",16),0);
+    GRIB_CHECK(grib_set_double_array(h,"values",values,size), 0);
+    free(values);
+    return GRIB_SUCCESS;
+}
+
+void do_encode(void *data);
+
+/* Structure for passing data to threads */
+struct v {
+    size_t number;
+    char *data;
+};
+
+void *runner(void *ptr); /* the thread */
+
+int main(int argc, char **argv)
+{
+    size_t i;
+    int thread_counter = 0;
+    int parallel=1, index=0, c=0;
+    const char* prog = argv[0];
+    char* mode;
+    if (argc<5 || argc>7) {
+        fprintf(stderr, "Usage:\n\t%s [options] seq sample numRuns numIter\nOr\n\t%s [options] par sample numThreads numIter\n", prog, prog);
+        return 1;
+    }
+    
+    while ((c = getopt (argc, argv, "dcw")) != -1) {
+        switch (c) {
+            case 'd': opt_dump=1; break;
+            case 'c': opt_clone=1; break;
+            case 'w': opt_write=1; break;
+        }
+    }
+    index = optind;
+    mode = argv[index];
+    INPUT_FILE = argv[index+1]; /* Has to be the name of a sample file (without tmpl extension) */
+    NUM_THREADS = atol(argv[index+2]);
+    FILES_PER_ITERATION = atol(argv[index+3]);
+
+    if (strcmp(mode,"seq")==0) {
+        parallel = 0;
+    }
+    if (parallel) {
+        printf("Running parallel in %ld threads. %ld iterations (prod=%ld)\n", NUM_THREADS, FILES_PER_ITERATION, NUM_THREADS*FILES_PER_ITERATION);
+        printf("Options: dump=%d, clone=%d, write=%d\n", opt_dump, opt_clone, opt_write);
+    } else {
+        printf("Running sequentially in %ld runs. %ld iterations\n", NUM_THREADS, FILES_PER_ITERATION);
+    }
+
+    {
+        pthread_t workers[NUM_THREADS];
+        for (i = 0; i < NUM_THREADS; i++) {
+            struct v *data = (struct v *) malloc(sizeof(struct v));
+            data->number = i;
+            data->data = NULL;
+
+            if (parallel) {
+                /* Now we will create the thread passing it data as an argument */
+                pthread_create(&workers[thread_counter], NULL, runner, data);
+                /*pthread_join(workers[thread_counter], NULL);*/
+                thread_counter++;
+            } else {
+                do_encode(data);
+            }
+        }
+
+        if (parallel) {
+            for (i = 0; i < NUM_THREADS; i++)  {
+                pthread_join(workers[i], NULL);
+            }
+        }
+    }
+
+    return 0;
+}
+
+void *runner(void *ptr)
+{
+    do_encode(ptr);
+    pthread_exit(0);
+}
+
+void do_encode(void *ptr)
+{
+    /* Cast argument to struct v pointer */
+    struct v *data = ptr;
+    size_t i;
+    char output_file[50];
+    time_t ltime;
+    struct tm result;
+    char stime[32];
+    grib_handle *hs = NULL;
+
+    hs = grib_handle_new_from_samples(0, INPUT_FILE);
+
+    for (i=0; i<FILES_PER_ITERATION;i++) {
+        grib_handle *h = grib_handle_clone(hs);
+        if (opt_write) {
+            sprintf(output_file,"output/output_file_%ld-%ld.grib", data->number, i);
+            encode_values(h,output_file);
+        } else {
+            encode_values(h,NULL);
+        }
+        grib_handle_delete(h);
+    }
+
+    ltime = time(NULL);
+    localtime_r(&ltime, &result);
+    strftime(stime, 32, "%H:%M:%S", &result); /* Try to get milliseconds here too*/
+    /* asctime_r(&result, stime); */
+
+    printf("%s: Worker %ld finished.\n", stime, data->number);
+    grib_handle_delete(hs);
+}
diff --git a/tests/grib_ecc-604.c b/tests/grib_ecc-604.c
index 055d1e8ac..2f2d268d7 100644
--- a/tests/grib_ecc-604.c
+++ b/tests/grib_ecc-604.c
@@ -1,5 +1,5 @@
 /*
- * Test for ECC-604: Each thread creates a new GRIB handle, clones it and writes it out
+ * Test for ECC-604: GRIB decoding/encoding sequentially and parallel with POSIX threads
  */
 #include <time.h>
 #include <pthread.h>