The reactions of trialkylalumiuiums (R3Al) with dialkylaluminium alkoxides (R2AlOR") have been studied by p.m.r. spectrometry, in the cases where R = Me, R' = Et, and R = Et, R' = Me, and where R" = Me, Pr1, But. It has been established that R is exchanged for R' when R" = Pr1 and But. The ease of exchange depends strongly upon the nature of R".