Potassium niobate crystals were grown from high temperature solutions using the floating zone pulling-down technique. The starting solution compositions of K and Nb were changed from K:Nb = 50:50 to 58:42. The lattice parameter, lattice volume and phase transformation temperature depended on the starting solution compositions. The solid solution region near the KNbO3 crystals was estimated to be expanding to a K-rich composition. © 2006 Elsevier B.V. All rights reserved.