This study aimed to evaluate the effect of pressurized CO₂, N₂ and atmospheric air against the immature stages and adults of two secondary insect species of stored products [Oryzaephilus surinamensis (L.) and Stegobium paniceum (L.)]. The insects were exposed to 5 levels (1-5 bars) of the pressurized gases in a metal gas cylinder for two exposure periods (one day and two days) at average of 20°C. The results showed generally that, Co₂ was the most effective as it induced the highest mortality percentages followed by N₂ then atmospheric air. Sensitivity of the two tested insect species to CO₂ and N₂ was approximately the same, while S. paniceum was more sensitive to the pressurized air than O. surinamensis. Egg stage of the two insect species was the more tolerant stage, while adult stage exhibits the highest level of sensitivity to all tested gases for any level of pressure and the both periods of exposure. Larvae of S. paniceum as exceptional case were more tolerant to the pressurized CO₂ than the other stages. It was noticed also that mortality of all insect stages of both species was significantly increased as the exposure period to the tested gases increased. Mortality of insects increased as the level of gas pressure increased recording the highest percentages of insect mortality at the highest level of gas pressure (5 kg/cm²).