H NMR chemical shifts d OH of the proton in the hydroxyl group of n-butanol and tert-butanol have been measured as function of mixture composition in the binary mixtures n-butanol + cyclohexane, tertbutanol + cyclohexane, and n-butanol + pyridine at 303, 313 and 323 K. In addition the molar excess enthalpy H E of n-butanol + pyridine has been determined as a function of the mixture composition at 298 K using a flow calorimeter. The ERAS (extended real associated solution) model has been applied for describing simultaneously the data of d OH and H E for n-butanol + cyclohexane accounting for self association of n-butanol via hydrogen bonding. The mixture of n-butanol + pyridine was treated similarly using the ERAS model considering self association of n-butanol as well as cross association of n-butanol with pyridine. The results obtained indicate that self association in n-butanol and tert-butanol as well as cross association between n-butanol and pyridine play an important role in these mixtures. The ERAS model is able to describe the dependence of d OH and H E on mixture composition and temperature for all mixtures with a minimum of adjustable parameters providing a realistic insight into the liquid structure of these systems.y Electronic supplementary information (ESI) available: Experimental chemical shifts d OH of alcohol mixtures referred to TMS (Table S1) and molar excess enthalpies H E of n-butanol(1) + pyridine(2) mixtures at 298 K (Table S2). See