Electron drift velocities have been measured in ethylene, acetylene, ethane, propane, methyl chloride, dimethyl ether, methanol and phosphine at 293°K and for 0.06⩽E/P⩽20 V cm–1 torr–1. They are used in conjunction with previously-determined Townsend energy coefficients to calculate momentum transfer cross-sections and fractional energy losses. The results are discussed qualitatively for each gas in terms of elastic and inelastic processes.