We present a short summary of the assembly procedure of a 10 × 10 cm2 CERN prototype triple GEM Chamber at the Universidad de los Andes, Bogota, Colombia. High voltage tests were performed at each step of the detector assembly, checking for stability of the GEM foils under high voltage. We report on the functionality of the assembled GEM chamber for a gas mixture of 75% Ar – 25% CO2 at one atmosphere pressure and room temperature. We study its response to gamma radiation from 55Fe and to muons resulting from cosmic rays. In particular we study the energy resolution, time and position sensitivity of the chamber and its gain, its charge multiplication factor.