The density, rho, and two derived properties, isothermal compressibility, kappa(T), and the coefficient of cubic expansion, alpha(P), were obtained for the mixtures of 1-methyl-4-(1-methylethenyl)-cyclohexene, known as limonene, and (1S,5S)-6,6-dimethyl-2-methylenebibyclo[3.1.1]heptane, known as beta-pinene, for nine different compositions and the pure components at five pressures from 20 MPa to 40 MPa and six temperatures from 283.15 K to 358.15 K. The experimental uncertainty for rho, kappa T, and alpha(P) were respectively +/- 0.5 kg . m (3), +/- 14 TPa (1), and +/- 0.005k K (1), with k = 2 for all of them. Density behaviour with temperature and pressure was as expected. The values of alpha(P) and kappa(T) increase with temperature and decrease with increasing pressure. Two different equations of state, conventional SAFT and PC-SAFT, were applied to predict the densities of the mixture. The best predictions were achieved with PC-SAFT. (C) 2011 Elsevier Ltd. All rights reserved.