Large single-grain (Sm/Y)(1.8)Ba2.4Cu3.4Oy [(Sm/Y)1.8] high T-c composite superconductors with/without CeO2 addition were systematically investigated by top-seeded melt growth (TSMG) process in air atmosphere. A melt-textured Nd1.8Ba2.4Cu3.4Oy (Nd1.8) single crystal was used as a seed for achieving the c-axis alignment large grains perpendicular to the surface of(Sm/Y)1.8 composite oxides. The size of(Sm/Y)(2)BaCuO5 [(Sm/Y)211] nonsuperconducting inclusions of the melt-textured (Sm/Y)1.8 samples with CeO2 addition were remarkably reduced and uniformly distributed within the (Sm/Y)Ba2Cu3Oy [(Sm/Y)123] matrix except in the region very close to the Nd1.8 seed crystal. In both samples, (Sm/Y)1.8 and (Sm/Y)1.8 with CeO2 addition, showed an onset T-c > 92 K and sharp transition. (C) 1999 Elsevier Science B.V. All rights reserved.