Density data (196 points) for 1-phenyldecane (decylbenzene) and for 1-phenylundecane (undecylbenzene) at several temperatures between (293.15 and 353.15) K and pressures up to 65 MPa are reported. A vibrating tube densimeter with an uncertainty of ±5 × 10-4 g·cm-3 was used to perform these measurements. The experimental density data were fitted with the Tait-like equation with standard deviations ≤1.5 × 10-4 g·cm-3. The isobaric thermal expansivity, αp, and the isothermal compressibility, κT, have been evaluated, calculating these derivative density properties using the Tait-like equation.