This invention relates to the disposal of aluminum hydrocarbyl, aluminum hydrocarbyloxy, aluminum halide or aluminum hydride waste materials. Such materials are used as catalysts and may be present alone as well as in combination with similar compounds of other elements typically of Group IV-B, V-B, VI-B, VII-B or VIII. The present disposal process seeks to minimize environmental pollution and provide a product that is suitably used as land-fill. In the process of the invention, a system containing an aluminum hydrocarbon, hydrocarbonoxy, halide or hydride waste stream either with or without a co-present compound of another element as set forth is reacted with a hydroxide or carbonate of a Group I-A, II-A, IV-A, or V-A element under substantially anhydrous conditions. The reaction is comparatively mild and is suitably conducted in ordinary steel equipment without excessive corrosion problems. Diluents co-present with the waste materials are recovered for recycle in anhydrous form without requiring drying.