Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) have been employed to study the adsorption and interaction of gamma-glycidoxy propyl trimethoxy silane (GPS) with grit-blasted aluminium. GPS displaces adventitious hydrocarbon either by covalent bond formation between GPS and aluminium, or adsorption, when GPS is deposited on the aluminium. ToF-SIMS fragments present at a nominal mass m/z=71 were peak-fitted to seven peaks by using CasaXPS Software. AlOSi(+) and Si(+) were used to establish a relationship between covalent bond formation and the adsorption process. It is found that the adsorption isotherms of Si(+) relating to the adsorption of GPS were of the Langmuir type. The interfacial bonding between GPS and aluminium is mainly covalent at low solution concentrations. At higher concentrations (greater than 4.5 x 10(-4) M) all the sites for the covalent bond formation appear to be occupied while these for the acid-base interaction are still available and then become fully occupied at solution concentrations of 4.5 x 10(-2) M and above.