From Borland non-tech forum, ozbear wrote:

Q: How do I get the hexadecimal string representation of an integer?
A1: s = String.Format('{0:X8}',yourint); // upper case hex
A2: s = String.Format('{0:x8}',yourint); // lower case hex

Q: How do I get the hexadecimal string representation of an character?
A1: s = String.Format('{0:X4}',(int)yourchar); // upper case hex
A2: s = String.Format('{0:x4}',(int)yourchar); // lower case hex

In the integer example, yourInt.ToString('X8') is another option.