Density functional theory (DFT) calculations are used to investigate the stability on SiC(0001) surfaces of different chemical groups -NH 2 , -NO 2 , -CH 3 , -OH, -SH and -CN. The adsorption stability decreases in the order -NO 2 >−OH>−NH 2 >−SH>−CN>−CH 3 . The stability of the single molecule-substrate bond is strongly influenced by the polarizability, which in turn depends on different parameters such as the electronegativity, atomic size and chemical environment. In a further step, methyl (−ACH 3 ) and phenyl (−AC 6 H 5 ) substituted groups are also considered and similar behaviour is observed. The inductive effect of the -CH 3 or -C 6 H 5 groups modifies the polarization of the Si adatom-molecule bond and the steric hindrance due to their size influences the molecular orientation. These two parameters affect the calculated adsorption energy, and are more important for –C 6 H 5 substituent. This study provides clear tendencies that can be applied to more complex systems. Comparison of the adsorption of two large molecules, H 2 Pc (metal-free phthalocyanine) and PTCDI (perylene tetracarboxylic diimide) on the SiC(0001) surface is presented as an example.