Densities of the missile fuel JP-10 were measured with two vibrating-tube densimeters. The combined range of the data is from 270 to 470 K, with pressures up to 30 MPa. The speed of sound in the fuel was measured with a propagation time method at ambient pressure from 278.15 to 343.15 K. The results for density and speed of sound at ambient pressure were combined to obtain the adiabatic compressibility. Correlations are reported that represent the temperature and pressure dependence of the experimental density data within their estimated uncertainty. The properties of JP-10 are compared to those of other previously measured jet and rocket fuels.