A facile spray pyrolysis processing of ternary Cu2SnS3and Cu2Sn1-xGexS3absorbers is presented. The Cu2SnS3and Cu2Sn1-xGexS3thin films were sprayed onto both glass and Mo substrates at 350 °C and then annealed at 550 °C with S and SnS/GeS crystals. The impacts of germanium incorporation on the properties and solar cell device performance of the Cu2SnS3layers were studied. X-ray diffraction and Raman measurements confirmed the monoclinic crystal structure of both Cu2SnS3and Cu2Sn1-xGexS3layers, with a slight peak shift observed in the Cu2Sn1-xGexS3samples due to the substitutional incorporation of Ge into the Sn site in the Cu2SnS3lattice. The introduction of Ge also increased the optical bandgap from 0.93 eV for Cu2SnS3to 0.99 eV for Cu2Sn1-xGexS3samples. Furthermore, Cu2Sn1-xGexS3layers exhibited enhanced grain growth, leading to an improved device performance from 1% for Cu2SnS3to 2.1% for Cu2Sn1-xGexS3solar cells.