High order optical nonlinearities of C 6 0 - and C 7 0 -toluene solutions are studied in the nanosecond time regime, employing the transient degenerate wave mixing technique. The intensity dependence of the high order signals of the solutions is investigated. The ratios χ ( 2 n + 3 ) e f f / χ ( 2 n + 1 ) e f f are determined to be of the order of 10 - 6 and 10 - 5 for C 6 0 and C 7 0 respectively.