We describe experimental studies of cubic nonlinear optical properties performed in reflection mode on thin films of polyaniline. It is shown that pump-probe and degenerate four-wave mixing reflection techniques are sensitive enough to obtain readily detectable nonlinear optical signals from polyaniline with femtosecond pulses at light intensities on the order of 100 GW/cm(2) . The results are compared with previous studies indicating that nonlinear coefficients of polyaniline are in the range of vertical bar n(2)vertical bar = 10(-12)-10(-11) cm(2)/W and that the relaxation of the nonlinear effects involves picosecond range processes.