This article involves computer simulation and surface analysis by nuclear techniques, which are non-destructive. The “energy method of analysis” for nuclear reactions and elastic scattering is used. Energy spectra are computer simulated and compared with experimental data, giving target composition and concentration profile information. The method is successfully applied to depth profiling of 18O and 12C nuclei in thick targets through the 18O(p,α0)15N and 12C(d,p0)13C reactions, respectively. Similarly, elastic scattering of (4He)+ ions is applied to determination of concentration profiles of O and Al for a thick target containing a thin film of aluminium oxide.