Isobraric p-T-x-y values for four binary mixtures composed of several butyl esters (from methanoate to butanoate) with n-propanol at 101.32 kPa have been measured using a dynamic method, All mixtures presented positive deviations from ideality and they were found to be thermodynamically consistent with the point-to-point test, being then correlated with suitable equations. An azeotrope at x(1) = 0.300 and T = 363.7 K was found for the mixture (x(1) butyl methanoate+x(2)n-propanol). The group contribution models gave acceptable estimations for the gamma(1) values.