Sugar cane bagasse is an industrial waste which is used worldwide as fuel in the same sugar-cane industry. The combustion yields ashes containing high amounts of unburned matter, silicon and aluminium oxides as main components. These sugar-cane bagasse ashes (SCBA) have been chemically, physically and mineralogically characterized, in order to evaluate the possibility of their use as a cement-replacing material in the concrete industry. Determination of parameters such as carbon content (by thermal analysis methods), presence of crystalline material (by X-ray diffractometry), granulometric distribution (by laser diffraction in water suspensions), morphology of particles (by scanning electron microscopy) and reactivity towards lime (pozzolanic activity by thermogravimetric monitoring in lime/SCBA and cement/SCBA pastes) have been carried out.