The invention relates to a process for preparing trialkylmetal compounds of the general formula R3M (where M=metal of group IIIA of the Periodic Table of the Elements (PTE), preferably gallium or indium, and R=C1-C5-alkyl, preferably methyl or ethyl).The process is based on the reaction of metal trichloride (MeCl3) with alkylaluminium sesquichloride (R3Al2Cl3) in the presence of at least one alkali metal halide as auxiliary base. The reaction mixture is heated to a temperature above 120° C. and the trialkylmetal compound is separated off from the reaction mixture via a separator, with partially alkylated products being at the same time recirculated to the reaction mixture. In a further step, the reaction mixture is heated to a maximum of 350° C. and the remaining alkylated and partially alkylated products are separated off. The products obtained in this way can optionally be recycled in the process.The process displays a high yield of trialkylmetal compound and also a high metal utilization; the products are used as precursors for MOCVD processes.