Molar enthalpies of dissolution, Delta H-sln(m), of decyl-, dodecyl-, tetradecyl-and hexadecyl-trimethylammonium bromide salts (RMe3NBr) in water have been measured calorimetrically as a function of concentration and temperature. Standard state values, Delta H-sln(m)o, were obtained by extrapolation to infinite dilution and showed a smooth variation with the number of carbon atoms, n(C), in the alkyl chain R, unlike their shorter congeners (n(C) <= 6). The corresponding molar isobaric heat capacity changes, Delta C-sln(p,m)o, were calculated from the temperature dependence of Delta H-sln(m)o and also varied smoothly with n(C) but were more than an order of magnitude greater than those of their shorter congeners, probably reflecting a marked increase in hydrophobicity with increasing n(C). The behaviour of the RMe3NBr salts was found to parallel broadly that of the symmetrical tetraalkylammonium salts, R4NBr. (C) 2014 Elsevier Ltd. All rights reserved.