This paper presents the development and implementation of multi-agent based software application for the analysis of generator bidding behavior in the Colombian electricity market. This application allows calculating the energy pre-dispatch in the electricity market. The market characteristics, which define the market as a multi-agent system, are included. The agents represent generators, structure, operating and rules. Different models were developed in order to implement the generator agents' behavior and those reflecting the best results were selected. The information used for modeling these agents was taken from the data base of the market operator (XM). Several simulations were carrying out to verify the systems behavior comparing them to the real market.