This work focuses on the production of glass and glass-ceramics by using industrial wastes or by-products,e.g., two fly ashes from the combustion of lignite, a slag from the production of Fe-Ni and a slag from the making of steel.Vitrification took place at 1 350°-1 450℃ and crystallization was achieved by heat treatment at 900, 950 and 1 000℃.The capability of the waste to be vitrified and subsequently devitrified was determined by XRD techniques. The crystalline phase depends greatly on the structure of the by-product and the heat treatment. The final products showed low leachability and good hardness.