If you want to enter characters as HEX numbers, you can quote HEX numbers with single quotes and a prefix of (X), or just prefix HEX numbers with (0x). A HEX number string will be automatically converted into a character string, if the expression context is a string. Here are some good examples:

SELECT X'313233' FROM DUAL;

123

SELECT 0x414243 FROM DUAL;

ABC

SELECT 0x46594963656E7465722E636F6D FROM DUAL;

GlobalGuideLine.com