A quantitative analytical method for 3,5-di-t-butyltoluene in reaction mixture by gas chromatography with methyl benzoate as internal standard is reported. A stainless steel column of 2m x 3mm i.d. packed with 15% FFAP/Chromosorb W/AW (60-80 mesh) and flame ionization detector were used with column temperature of 180 degrees C and injection port and detector temperatures of 250 degrees C. There was a good linear calibration curve in the range from 1.1 to 9.2 microg (r = 0.9990, n = 8). It was taken 10 minutes to complete an analysis.