The　structure　and　electrical　properties　of　Cr2O3-doped　Pb(Zn1/3Nb2/3)(0.20)(Zr0.50Ti0.50)(0.80)O-3　system　(0.2PZN-0.8PZT)　were　described　in　this　paper.　Materials　with　pure　perovskite　structure　were　fabricated　by　the　columbite　precursor　method.　Addition　of　Cr2O3　stabilized　the　tetragonal　phase　against　the　rhombohedral　one,　moving　morphotropic　phase　boundary　(MPB)　composition　toward　the　PbTiO3-deficient　side.　The　grain　size　was　steadily　enhanced　when　small　amounts　of　Cr2O3　were　added　to　system.　However,　addition　Of　Cr2O3　above　the　solubility　of　0.3　wt.%　inhibited　the　grain　growth　due　to　accumulation　of　Cr　ion　at　the　grain　boundary.　The　values　of　electromechanical　coupling　factor,　k(p),　piezoelectric　constant,　d(33)　are　optimized　for　0.3　wt.%　Cr2O3-doped　samples　(k(p)　=　0.70,　d(33)　=　491　pC/N),　which　suggested　that　the　effects　of　grain　size　plays　a　dominant　role　on　improving　the　piezoelectric　properties　than　that　of　oxygen　vacancies　in　the　low　Cr2O3　doping　region　of　0-0.3　wt.%.　(C)　2004　Elsevier　B.V.　All　rights　reserved.