The influences of the phosphate and glycocol buffers on the Griess’s coloration which we employed to estimate NO_2, NH_2OH, acetoxime and pyruvic acid-oxime, and the stabilities of these substances in the buffer solutions at 100°for 10 minutes and at 40° for 24 hours were studied. Some unfavourable effects were observed but found to be avoided by dilution of the buffers. And, the best condition for the estimation of pyruvic acid- and α-ketoglutaric acid-oximes by this colour reaction were determined.