Abstract The equilibrated grain boundary groove shapes of solid Sn3Sb2 in equilibrium with the Sn–Sb peritectic liquid have been observed from quenched sample with a radial heat flow apparatus. The Gibbs–Thomson coefficient, solid–liquid interfacial energy and grain boundary energy of solid Sn3Sb2 have been determined from the observed grain boundary groove shapes. The variation of thermal conductivity with temperature for solid Sn3Sb2 and peritectic solid has been measured up to five degree below the meting temperature with a radial heat flow apparatus. The ratio of thermal conductivity of liquid phase to solid phase for Sn–7.8 at.%Sb alloy at the melting temperature has also been measured with a Bridgman type growth apparatus.