The multiphase equilibration technique has been used to measure the equilibrium angles that develop at the interphase boundaries of a solid-liquid-vapour system after annealing and also the surface (gamma(SV)) and the grain-boundary, (gamma(SS)) energies of polycrystalline yttria-stabilized zirconia (8 mol% Y2O3). The data was recorded in the temperature range 1573-1873 K. Linear temperature functions were obtained for the surface energy gamma(SY) (J m(-2)) = 1.927 - 0.428 x 10(-3)T and for the grain-boundary energy gamma(SS) (J m(-2)) = 1.215 - 0.358 x 10(-3)T.