Process for preparing a pentane-1,5-diamine of the formula ##STR1## where R.sup.1 represents a variety of organic radicals including alkyl which can bear substituents such as hydroxyl, halogen, alkoxy, carbalkoxy, carboxyl, alkylamino, cycloalkyl or aryl, andR.sup.2 and R.sup.3 independently of one another, represent hydrogen or have the same meanings as R.sup.1 or together are a C.sub.4 -C.sub.7 -alkylene chain which is unsubstituted or substituted by one to five C.sub.1 -C.sub.4 -alkyl groups,which comprises:(a) reacting a .gamma.-cyanoketone of the formula ##STR2## where R.sup.1, R.sup.2 and R.sup.3 have the meanings given above, with excess ammonia in a first reaction space on an acidic heterogeneous catalyst at 20.degree.-150.degree. C. and 15-500 bar, and(b) hydrogenating the resulting reaction product in a second separate reaction space in the presence of excess ammonia on a cobalt, nickel or noble metal catalyst at 50.degree.-180.degree. C. and 30-500 bar.Novel pentane-1,5-diamines are obtained, in which R.sup.1 must contain at least two carbon atoms if R.sup.2 and R.sup.3 are both hydrogen. These new compounds containing two primary amine groups possess advantageous properties of lower volatility and also greater asymmetry (with different reactivity of the two amine functions). They provide useful curing agents for epoxides and act as improved components of polyamides.