Abstract: We synthesized a bismuth-rich bismuth sulfide (Bi2+xS3) to improve the electrical conductivity. A percolated composite was obtained by mixing Bi2+xS3 with commercial Bi2S3 so that the other thermoelectric parameters were not compromised. The Bi2+xS3 acted as a conductive percolating channel within the Bi2S3 matrix. This percolation approach retained the high Seebeck coefficient of the Bi2S3 matrix while improving the electrical conductivity. A dimensionless figure of merit (zT) up to five times that of the pure Bi2S3 sample was achieved.