Radiation-induced gas evolution rates were measured at room temperature for four organic liquids: SAE-30 motor oil, brake fluid, transmission fluid, and vacuum pump oil Cobalt-60 gamma radiation was used at an average dose rate of 7.0 × 104 rad/h. Measured gas evolution rates varied from 1.60 × 10−3 ℓ (gas)/ℓ. (fluid) per megarad for SAE-30 motor oil to 7.07 × 10−3 ℓ (gas)/ℓ (fluid) per megarad for the brake fluid. The onset of gas evolution appears to occur near the minimum in the viscosity variation with absorbed dose.