An isothermal titration calorimeter was used to measure the excess molar enthalpies (H-E) at T = 298.15 K for five binary systems: 1-methyl-3-octyl-imidazolium tetrafluoroborate (OmimBF(4)) + alcohols (ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-pentanol). The values of HE were found to be all positive for the five systems and were fitted with the Redlich-Kister polynomial and the UNIQUAC mode. The magnitude order of HE for the five systems was explained by the balance between the magnitude orders of enthalpies of the alcohol/alcohol and the alcohol/OmimBF(4) interactions.