Off-congruent lithium niobate single crystals were grown by the Czochralski method with K2O added to the congruent melts in a concentration varying between 2 and 10.5 wt%. The Li/Nb ratio was determined by means of indirect methods such as the fundamental absorption edge positon. the IR vibrational spectrum. lattice parameters and the variation of the refractive indices. The data presented in this work show that the Li/Nb ratio can be controlled by the amount of K2O added to the congruent melt. Moreover. the techniques employed For characterization are good tools for the determination of the Li/Nb ratio.