This review deals with the synthesis, properties and applications of dialkyl complexes of the type LxMR2 (R = alkyl; Lx = ligands; M = transition metals of groups VI to X. Discussion on the comparison with analogous monoalkyl-metal complexes is also carried out. Possible reactivity patterns include: insertions of small molecules into the metal and carbon σ-bond, cyclometalations, oxidative addition, transmetalation, and thermal decomposition; these are discussed. The influence of various factors on the stability and reactivity of these title compounds is described. The applications and intermediacy of transition metal-dialkyl species in various catalytic reactions are highlighted. © 2008 Elsevier B.V. All rights reserved.