The adsorption and thermal decomposition of trimethylindium (TMIn) on Si(110) were studied with XPS, UPS and HREELS techniques. TMIn molecules were found to adsorb on the surface at 120 K with a partial dissociation of In-C bonds, similar to the cases of TMIn on Si(111)-7×7 and Si(100)-2×1, but to a larger extent. The cracking of the In-C bonds continued at 250 K and was completed at 550 K, as indicated by the disappearance of the In-C characteristic peaks at 61 meV in the HREELS and at 3.5 eV in the UPS spectra, as well as by the observed peak-shifting for both C(1s) and In(3d 5 2) photoelectrons in the XPS spectra. At 550 K, C-H bond breaking also occurred, indicated by the fact that the peak at 258 meV in the HREELS and the peak at 5.3 eV in the UPS spectra due to Si-H species could be observed. Above 630 K, In species started to form an island on and subsequently desorb from the surface; this was evidenced by the large peak-shifting in both In(3d 5 2) XPS and In(4d) UPS results and by the attenuation of the In(3d 5 2) XPS signal intensity, respectively. At T>950 K, the C-H bond scission and the H and In desorption were complete, with C species left on the surface forming silicon-carbide.