Very reactive, monodisperse (4.0 ± 0.5 nm) spherical indium(0) nanoparticles have been generated in situ, in a simple, mild and efficient way, by fast reduction of commercially available indium(III) chloride with lithium sand and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) in THF, at room temperature, and in the absence of any anti-agglomeration additives or ligands. The as-synthesized bare InNPs were applied for the allylation of a variety of aldehydes and ketones. For most of the compounds tested, the corresponding homoallylic alcohols were obtained as the major product in good to excellent yield.