The density of the asymmetrical binary system composed of ethanol and methylcyclohexane has been measured under pressure using a vibrating tube densimeter. The measurements have been performed for eight different compositions as well as the pure compounds at eight temperatures in the range 283.15 K to 353.15 K and ten isobars up to 45 MPa. The uncertainty for the reported densities is estimated to be 0. 1 kg center dot m(-3). A non-monotonical behavior involving a minimum in the density versus composition has been found for this binary system. The measured data have been used to study the behavior and influence of temperature, pressure and composition on the excess molar volume, the isothermal compressibility, and the isobaric thermal expansion, revealing that a volume expansion occurs for this binary system. The results have been interpreted as due to changes in the intermolecular distances or free-volume, disruption of the order molecular structure and the breaking of hydrogen bonds within the self-associating alcohol. (c) 2005 Elsevier Ltd. All rights reserved.