The density and speed of sound of liquid methylcyclohexane and propylcyclohexane were measured with two vibrating-tube densimeters and a time-of-flight method, respectively. The combined range of the data is from 270 to 470 K with pressures to 40 MPa. The estimated uncertainties of the density and the speed of sound data are each 0.1%. The experimental data are represented by correlations within their estimated uncertainty. Comparisons with literature data show good agreement in overlapping ranges. Data presented here constitute a substantial addition to the previously available data for these two compounds.