diff --git a/README.md b/README.md
index d3d2975..4bcd81b 100644
--- a/README.md
+++ b/README.md
@@ -46,13 +46,21 @@ built, signed, fulfilled and serialized.
 Now, the transaction can be submitted to the BigchainDB nodes.
 
 ```
-  /* inputs: operation, asset, metadata, base_pubkey(public key in base58)
+  /* prepare for 'CREATE' operation
+  * (The keys on the JSON must be in alphabetical order)
+  * inputs: operation, asset, metadata, base_pubkey(public key in base58)
   * output: tx
-  * 'operation' can be either 'C' or 'T' for CREATE and TRANSFER respectively.
-  * when 'operation' is CREATE then 'asset' can be arbitrary. (The keys on the JSON must be in alphabetical order)
-  * but when 'operation' is TRANSFER then 'asset' must be the transaction id of the asset which is to be tranfered.
   */
-  prepare_tx(BIGCHAIN_TX *tx, const char operation, char *asset, char *metadata , char *base_pubkey);
+  void prepare_CREATE(BIGCHAIN_TX *tx, char *asset, char *metadata, char *base_pubkey);
+
+  /* prepare for 'TRANSFER' operation
+  * (The keys on the JSON must be in alphabetical order)
+  * asset = transaction id of the asset to be transferred
+  * fulfills = transaction id of the latest TRANSFER, which is the same as asset if this is the first time it is being transferred.
+  * inputs: operation, fulfills, asset, metadata, base_pubkey(public key in base58)
+  * output: tx
+  */
+  void prepare_TRANSFER(BIGCHAIN_TX *tx, char *fulfills, char *asset, char *metadata, char *base_pubkey);
   
   /* inputs: tx, tx_id(same as 'asset' above, only needed for TRANSFER) , priv_key, pub_key(public key in hexadecimal base) , maxlen(maximum length of string)
   * output: json
diff --git a/inc/transaction.h b/inc/transaction.h
index 2c3e31d..438782e 100644
--- a/inc/transaction.h
+++ b/inc/transaction.h
@@ -42,7 +42,8 @@ void bigchain_sign_transaction(uint8_t *json_tx, uint16_t len, uint8_t *priv_key
 char *bigchain_build_json_inputs(BIGCHAIN_INPUT *inputs, uint8_t num_inputs, char *json_obj);
 char *bigchain_build_json_outputs(BIGCHAIN_OUTPUT *outputs, uint8_t num_outputs, char *json_obj);
 void bigchain_build_json_tx(BIGCHAIN_TX *tx, char *json_tx);
-void prepare_tx(BIGCHAIN_TX *tx, const char operation, char *asset, char *metadata, char *base_pubkey);
+void prepare_CREATE(BIGCHAIN_TX *tx, char *asset, char *metadata, char *base_pubkey);
+void prepare_TRANSFER(BIGCHAIN_TX *tx, char *fulfills, char *asset, char *metadata, char *base_pubkey);
 void fulfill_tx(BIGCHAIN_TX *tx, char *tx_id, uint8_t *priv_key, uint8_t *pub_key, uint8_t *json, uint16_t maxlen);
 
 #endif // _BIGCHAIN_TX_H_
diff --git a/src/transaction.c b/src/transaction.c
index ae34f3c..93dc65d 100644
--- a/src/transaction.c
+++ b/src/transaction.c
@@ -208,30 +208,45 @@ void bigchain_build_json_tx(BIGCHAIN_TX *tx, char *json_tx) {
   p = json_end(p);
 }
 
-/* 'operation'can be either 'C' or 'T' for CREATE and TRANSFER respectively.
- * when 'operation' is CREATE then 'asset' can be arbitrary. (The keys on the JSON must be in alphabetical order)
- * but when 'operation' is TRANSFER then 'asset' must be the transaction id of the asset which is to be tranfered.
- */
-void prepare_tx(BIGCHAIN_TX *tx, const char operation, char *asset, char *metadata, char *base_pubkey) {
+void prepare_CREATE(BIGCHAIN_TX *tx, char *asset, char *metadata, char *base_pubkey)
+{
   // Fill input struct
   memset(tx->inputs, 0, sizeof(BIGCHAIN_INPUT));
   memcpy(tx->inputs[0].owners_before[0], base_pubkey, strlen(base_pubkey));
   tx->inputs[0].num_owners = 1;
   tx->num_inputs = 1;
 
-  if (operation == 'C') {
-    memcpy(tx->operation, "CREATE", strlen("CREATE"));
-    memcpy(tx->asset, asset, strlen(asset));
-  } else if (operation == 'T') {
-    memcpy(tx->operation, "TRANSFER", strlen("TRANSFER"));
-    memcpy(tx->inputs[0].fulfills, FULFILL_PREFIX, FULFILL_PREFIX_LENGTH );
-    memcpy(tx->inputs[0].fulfills + FULFILL_PREFIX_LENGTH, asset, TX_ID_LENGTH );
-    memcpy(tx->inputs[0].fulfills + FULFILL_PREFIX_LENGTH + TX_ID_LENGTH, "\"\0", 2);
-    memcpy(tx->asset, ASSET_ID, ASSET_ID_LENGTH);
-    memcpy(tx->asset + ASSET_ID_LENGTH, asset, TX_ID_LENGTH );
-    memcpy(tx->asset + ASSET_ID_LENGTH + TX_ID_LENGTH, "\"\0", 2);
-  }
+  memcpy(tx->operation, "CREATE", strlen("CREATE"));
+  memcpy(tx->asset, asset, strlen(asset));
+  
+  memcpy(tx->metadata, metadata, strlen(metadata));
+  memcpy(tx->version, BDB_VERSION, strlen(BDB_VERSION));
+
+  // Fill output struct
+  memset(tx->outputs, 0, sizeof(BIGCHAIN_OUTPUT));
+  tx->outputs[0].amount[0] = '1';
+  memcpy(tx->outputs[0].details_public_key, base_pubkey, strlen(base_pubkey));
+  memcpy(tx->outputs[0].public_keys[0], base_pubkey, strlen(base_pubkey));
+  tx->outputs[0].num_public_keys = 1;
+  tx->num_outputs = 1;
+}
+
+void prepare_TRANSFER(BIGCHAIN_TX *tx, char *fulfills, char *asset, char *metadata, char *base_pubkey)
+{
+  // Fill input struct
+  memset(tx->inputs, 0, sizeof(BIGCHAIN_INPUT));
+  memcpy(tx->inputs[0].owners_before[0], base_pubkey, strlen(base_pubkey));
+  tx->inputs[0].num_owners = 1;
+  tx->num_inputs = 1;
 
+  memcpy(tx->operation, "TRANSFER", strlen("TRANSFER"));
+  memcpy(tx->inputs[0].fulfills, FULFILL_PREFIX, FULFILL_PREFIX_LENGTH );
+  memcpy(tx->inputs[0].fulfills + FULFILL_PREFIX_LENGTH, fulfills, TX_ID_LENGTH );
+  memcpy(tx->inputs[0].fulfills + FULFILL_PREFIX_LENGTH + TX_ID_LENGTH, "\"\0", 2);
+  memcpy(tx->asset, ASSET_ID, ASSET_ID_LENGTH);
+  memcpy(tx->asset + ASSET_ID_LENGTH, asset, TX_ID_LENGTH );
+  memcpy(tx->asset + ASSET_ID_LENGTH + TX_ID_LENGTH, "\"\0", 2);
+  
   memcpy(tx->metadata, metadata, strlen(metadata));
   memcpy(tx->version, BDB_VERSION, strlen(BDB_VERSION));
 
diff --git a/tests/test_sig.c b/tests/test_sig.c
index 07baa41..a905d7d 100644
--- a/tests/test_sig.c
+++ b/tests/test_sig.c
@@ -103,7 +103,7 @@ void test_bigchain_create_tx() {
   BIGCHAIN_TX tx;
   char json[3000] = {0};
   memset(&tx, 0, sizeof(BIGCHAIN_TX));
-  prepare_tx(&tx, TEST_OPERATION_CREATE, TEST_CREATE_ASSET, TEST_METADATA, base58_pubkey );
+  prepare_CREATE(&tx, TEST_CREATE_ASSET, TEST_METADATA, base58_pubkey );
   fulfill_tx(&tx, 0, privkey, pubkey, json, 3000 );
   TEST_ASSERT_EQUAL_STRING_LEN(C_tx_json, json, sizeof(C_tx_json));
 }
@@ -112,7 +112,7 @@ void test_bigchain_transfer_tx() {
   BIGCHAIN_TX tx;
   char json[2000] = {0};
   memset(&tx, 0, sizeof(BIGCHAIN_TX));
-  prepare_tx(&tx, TEST_OPERATION_TRANSFER, TEST_TRANSFER_ASSET, TEST_METADATA, base58_pubkey ) ;
+  prepare_TRANSFER(&tx, TEST_TRANSFER_ASSET, TEST_TRANSFER_ASSET, TEST_METADATA, base58_pubkey ) ;
   fulfill_tx(&tx, TEST_TRANSFER_ASSET, privkey, pubkey, json, 2000 );
   TEST_ASSERT_EQUAL_STRING_LEN(T_tx_json, json, sizeof(T_tx_json));
 }