The vapor pressure of pure tert-amyl methyl ether (TAME) was measured together with isothermal P-x data for mixtures of pentane + TAME and pentane + tert-amyl alcohol (TAOH) at temperatures between 70 and 110 degrees C. Also, activity coefficients at infinite dilution for the binary mixtures of TAME + TAOH were obtained in the 90-120 degrees C temperature range. The P-T-x data were correlated using the Peng-Robinson equation of state separately with the van der Waals and Wong-Sandler mixing rules.