FIELD: organic technology. SUBSTANCE: lactams are prepared by interaction of aliphatic aminonitrile with water. The process takes place in the presence of solid catalyst. Solid catalyst represents metallic phosphate having common formula (PO4)nHhM,(1mp)p where M is bivalent, trivalent, tetravalent or pentavalent element chosen of IIa, IIIb, IVb, Vb, VIb, VIIb, VIII, IIb, IIIa, IVa and Va groups of Periodic Table or mixture thereof. Or M= 0, then 1 mp is base impregnating compound comprising alkali or alkaline-earth metal or mixture thereof associated with counterion to provide electric neutrality, n=1,2 or 3, h=0,1 or 2, p is integer from 0 to 1/3 corresponding to molar ratio of 1 mp and (PO4)nHhM. EFFECT: increased selectivity of the reaction, increased yield of product increased living time of catalyst. 10 cl, 3 tbl
