The effect of temperature on development duration and on demographic parameters were tested on Tunisian population (Grombalia) of Neoseiulus californicus preying on Tetranychus urticae at 24, 30 and 35 deg C, under controlled conditions. The natural growth rate (rm) ranged from 0.203 days at 24 deg C, to 0.326 days at 30 deg C and 0.268 days at 35 deg C. The net reproduction rate (R0) has the highest value at 30 deg C with 23 females/female and was lower at 35 deg C than at 24 deg C (10 and 15 females / female in respect). The generation time (T) decreased with increasing temperature from 13.4 days at 24 deg C to 9.6 days at 30 deg C and 8.6 days at 35 deg C. The development time from egg to adult was two days shorter at 35 deg C (3.9 days) than at 24 deg C (5.9 days). It was 4.1 days at 30 deg C. The survival of immature, the fecundity and the adult female longevity were similar at 24 (84%, 30.7 eggs/female, 15.7 days) and 30 deg C (90%, 35.2 eggs/female, 14.8 days) but lowered at 35 deg C (in respect 72%, 21.9 eggs/ female and 10.7 days).