The equilibrated grain boundary groove shapes for the Al-Ti peritectic system were directly observed. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient for solid Al in Al-Ti solution has been determined to be (1.281 +/- 0.06) x 10(-7) K in with a numerical method. The solid-liquid interface energy for solid Al in Al-Ti solution has been obtained to be (170.72 +/- 16.22) x 10(-3) J m(-2) from the Gibbs-Thomson equation. The grain boundary energy for the same material has been calculated to be (332.01 +/- 35.19) x 10(-3) J m(-2) from the observed grain boundary groove shapes. (C) 2004 Elsevier B.V. All rights reserved.