The surface tension of a low molar mass liquid crystal (LMMLC), 4-cyano-4'-n-heptyloxybiphenyl (70CB), was measured in the nematic and isotropic phases using the pendant drop method. Also the contact angles formed by drops of 70CB in the nematic and isotropic phases on plates of polystyrene (PS) and of a liquid crystal polymer (LCP), were measured. Using those obtained values the interfacial tension between 70CB and PS and between 70CB and LCP were evaluated. The results were analysed from a thermodynamical point of view.