Third‐order nonlinear optical response of a cadmium texaphyrin solution at 532 nm was measured using time‐resolved degenerate four‐wave mixing with picosecond pulses. The molecules of cadmium texaphyrin exhibit a large optical nonlinearity, which arises from the excited‐state population. The dynamics of the nonlinear optical response show an evident fluence dependence. The temporal response is characterized by three components, a slower, a faster, and a fastest, which are attributed to populations of the first triplet excited state, the first singlet excited state, and the higher singlet excited state, respectively. ©1995 American Institute of Physics.