The effect on grain interior and grain boundary reactions by Cr addition to low gold content alloys were investigated by electric resistivity measurements, hardness tests, optical microscopic observations, and TEM observations. The grain interior reactions were accelerated by the chromium addition while grain boundary reactions were retarded, The formation of AuCu I type ordered phase in the grain interior was accelerated, and the T-T-T curve of AuCu I type ordered phase shifted to higher temperatures and shorter times with increasing chromium content.