An attempt was made to test the cavity model of electron localization in liquid hydrocarbons by measuring the effect of pressures up to 4000 bars on the radiation induced conductance of n-pentane, n-hexane, n-octane, cyclopentane, methylcyclohexane, and 2,2-dimethylbutane at 30°. Measurements at 3 and 56° were also made on n-hexane and n-octane. The relative induced conductance, i.e. the ratio of the induced conductance at pressure p to that at 1 bar, decreased with increasing pressure. The amount of decrease was slightly greater at low than at high temperatures. The behavior of 2,2-dimethylbutane was complex and is not understood. For the other liquids, it was concluded that the free ion yields remained constant or decreased somewhat with increasing pressure. An appreciable increase in the free ion yields, which is a possible implication of the cavity model of electron localization, did not occur. Therefore, either (a) the cavity model of electron localization in hydrocarbons is wrong, or (b) application of pressures up to 4000 bars did not appreciably alter the cavity concentrations in the liquids. Perhaps the cavity concentration is greatly reduced only by pressures great enough to cause a solid phase (glass or crystal) to form.