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 x 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 x 10(-4) g(.)cm(-3). The isobaric thermal expansivity, a(p), and the isothermal compressibility, kappa(T), have been evaluated, calculating these derivative density properties using the Tait-like equation.