The heat capacity per unit volume rho c(p) of four crude oil samples were measured at pressure up to 1 GPa and ambient temperature using the transient hot-wire method. It is shown that with rise of pressure the rho c(p) of the investigated samples increases linearly with an average value of 0.051 MJ/(m(3)center dot K) for each 0.1 GPa. The same growth rate of rho c(p) was observed for all the investigated samples.