Densities (p, rho, T, x(1)) of two binary n-alkane systems are reported from T = (313 to 363) K in the compressed liquid phase up to 25 MPa over the whole range of composition. The binary mixtures {x(1)n-heptane + (1-x(1))n-decane} and {x(1)n-octane + (1 -)n-decane} were prepared at compositions of (x(1) = 0.0531, 0.2594, 0.5219, 0.777, 0.952), and (x(1) = 0.0616, 0.2801, 0.5314, 0.7736, 0.9623), respectively. A measuring system based on a vibrating tube densimeter, DMA HPM from Anton Paar with data acquisition system was developed in order to obtain experimental densities. Water and nitrogen were used as reference fluids to calibrate the densimeter. Experimental methodology was checked by comparing the n-heptane and n-decane densities against multi-parameter equations proposed in the literature. Differences between both sets of data show a maximum deviation of 0.07%. Excess molar volumes, isothermal compressibility and isobaric thermal expansivity were computed from experimental densities. (C) 2011 Elsevier Ltd. All rights reserved.