Abstract: Using T. S. S. (4-Amino-N, N-Diethylaniline sulfate) as a developing agent, the cyan couplers were developed in the positive film. The photographic data had been shown to fit the Elveg-ard equation. The superdelocalizabilities (S_r^(K)) proposed by Fukui at the coupling sites of these couplers were calculated with HMO method as the chemical activities of the couplers. It has beem found that the S_r^(K) is a good parameter characterizing the chemical activity of the coupler. The o-substituent to the coupling site of the couplerwould have a steric effect on the coupling reaction.