The catalytic hydration of mono and dinitriles (dicyanoalkanes, DCAs) using nickel(0) catalysts of the type, [(dippe)Ni(eta(2)-N,C-R)] (R=-Me,-Ph,-(CH2)(2)-CN,-(CH2)(4)-CN) and p-toluenesulfonic acid monohydrate (PTSA) as a co-catalyst, is reported. In the cases where DCAs (adipo and succinonitrile) were used, both the activity and the selectivity for the process were affected by length of the internal chains of the substrates. A competitive decomposition of the amide products was observed to be favoured to a greater extent in the case of succinonitrile, resulting in extensive carbonization and formation of ammonia. The carbonaceous by-products were analysed by scanning electron microscopy (SEM). The use of nickel(II) sources was addressed in the presence and in the absence of PTSA, with the aim of comparing their reactivity with that displayed by nickel(0) catalysts. The results obtained from these studies suggest that activity of the catalyst is affected by the oxidation state of the metal, the use of nickel(0) Compounds resulting in better catalyst performance overall. (C) 2008 Elsevier B.V. All rights reserved.