Ti/Al multilayer thin films with modulation periods up to 100 nm were characterised at the nanoscale level. The Ti/Al multilayers were deposited onto stainless steel substrates by magnetron sputtering from Ti and Al targets. Time on flight secondary ion mass spectroscopy analyses were carried out in order to verify the layered structure and check both the effect of contaminants such as oxygen and the intermixing at the interfaces. Structural analyses were performed by X-ray diffraction and transmission electron microscopy. The deposition procedure gives rise to a nanometric multilayer structure, where elemental Ti and Al can be identified, even for the lowest period multilayer (4 nm). The multilayer films consist of a-Ti plus Al with nanometric grain sizes. The grain size is determined by the multilayer modulation period, having both similar values. In the as-deposited state no intermetallic compounds were detected. During the deposition process some intermixing occurred at the interfaces, which should assume some importance in decreasing the heat of the exothermic reaction between Ti and Al, particularly as the modulation period decreases.