Substituent effects on the potential energy surface of X2Ge=S (X = H, F, Cl, Br, CH3, and SiH3) were studied by using the B3LYP and CCSD(T) methods. Our theoretical investigations indicate that the kinetic and thermodynamic stabilities of substituted germanethiones are strongly dependent on the substituent. That is to say, dihalogen substitution can dramatically stabilize X2Ge=S with respect to XGe-SX. Thus, F2Ge=S, Cl2Ge=S and Br2Ge=S should be viable candidates for experimental observation.