The melting-freezing phase transition of gallium in a porous glass was studied by NMR and acoustical techniques. A depression of the freezing and melting phase transition temperatures and a pronounced hysteresis in the melting-freezing processes were found. An intricate 71 Ga NMR lineshape for liquid gallium was observed with a temperature coefficient of the Knight shift more than twice that measured for the bulk melt. The results are discussed on the basis of the Gibbs-Thompson equation and by means of a geometric freezing model.