The effect of substitution on the potential energy surfaces of HC equivalent to GeX (X = H, CH3, F, and Cl) were explored using density functional theory (B3LYP) and QCISD methods. The theoretical findings suggest that (H)(X)C=Ge: is the minimum on the singlet potential energy surface, regardless of the substituents (X) used. On the other hand, HC equivalent to GeX and XC equivalent to GeH are found to be local minima on the surface, but they are neither kinetically nor thermodynamically stable.