Abstract: The polarographic adsorptive wave of cadmium-meso-tetra(4-trimethyl-ammoniumphenyl) porphine (TTAPP) complex in sodium hydroxide solution has been studied. Ep=-1.23V (vs.SCE). The detection limit is 2×10^-8M. The peak height is linearly proportional to cadmium concentration over a range of 0.002 to 0.8μg ml^-1. In the presence of masking agents tartrate and ethylenediamine, more than 30 species of ions at certain concentration range do not interfere the determination. This method has been applied to the determination of trace amounts of Cd in fresh water, electroplating waste water and aluminium alloys. The mechanism of adsorptive wave has been discussed. The composition of Cd-TTAPPcomplex has been studied by "polarographic mole-ratio method". The results show that the Cd:TTAPPin complex is 1:1, the conditional stability constant of complex is β'= (7.7±0.6)×10₇. It agrees well with the results of spectrophotometry which Cd; TTAPP = 1:1 and β'=9.2×l0₇.