Surface tensions and refractive indices were measured for (lithium bromide + water + 1,3-propanediol), which can be proposed as a new potential working fluid in air-cooled absorption chillers. The mass ratio of lithium bromide to 1,3-propanediol is fixed at 3.5 : 1, an optimal value for avoiding crystallization problems. The experimental temperature ranged from 298.2 K to 323.2 K, and the lithium bromide mass fraction up to 0.659. Both the data of surface tension and refractive index were successfully correlated with simple polynomial equations with average absolute deviations (a.a.d.) of 0.189 and 0.032 per cent, respectively. (C) 2001 Academic Press.