Experimental surface tensions, measured with a drop volume tensiometer and the corresponding surface tension deviations for the binary mixtures of cyclohexane or methylcyclohexane with a cyclic ether (tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran or 2,5-dimethyltetrahydrofuran) are given at 25 and 40 ∘C. The results have been discussed in terms of lyophobicity and molecular interactions using the extended Langmuir isotherm. The model proposed by Patterson and Rastogi has been used to calculate the surface tensions of the pure components and of their mixtures at 25∘C; these calculations have been compared with the experimental results.