BaNbS3 phase was found to be stable in the composition range between x = 0.85 and 0.97 for BaNbxS3. The conduction nature was varied from semiconductive to metallic with increasing Nb content. Semiconductor-to-metal (S-M) transition was observed at similar to170 and similar to250 K in BaNb0.95S3 and BaNb0.97S3, respectively. BaTaSe3 phase was stable in the range between x = 0.90 and 0.95 for BaTaxSe3. BaTaxSe3 with x = 0.90 and 0.95 showed a semiconductor-to-semiconductor transition at similar to 140 K, which is characterized by a large jump of the resistivity from similar to10(6) to similar to10(12) Omega cm. Seebeck measurements showed electron conduction in both BaNbxS3 and BaTaxSe3. (C) 2004 Elsevier Ltd. All rights reserved.