Abstract The excess enthalpies H E m of [ x {BrCH 2 Cl or BrCH 2 CH 2 Cl or BrCH 2 CH 2 CH 2 Cl or BrCH 2 (CH 2 ) 2 )CH 2 Cl} + (1 − x ) {CH 3 (CH 2 ) 5 CH 3 or CH 3 (CH 2 ) 14 CH 3 or c -(CH 2 ) 6 } have been measured at the temperature 298.15 K. Mixing was endothermic at all x and the H E m s were found to vary in the sequence: BrCH 2 CH 2 Cl > BrCH 2 Cl > BrCH 2 CH 2 CH 2 Cl ≈ BrCH 2 (CH 2 ) 2 CH 2 Cl for mixing with CH 3 (CH 2 ) 5 CH 3 . This behaviour is similar to that found for mixing with CH 3 (CH 2 ) 14 CH 3 or c -(CH 2 ) 6 . From the results, qualitative information could be obtained about the so-called “proximity effect”.