A method of forming an image is described which comprises imagewise exposing a photosensitive material comprising a support having thereon a photosensitive copper (I) halide emulsion and that optionally contains silver halide and which has grains of the copper (1) halide crystal dispersed in a binder, and developing it with an alkaline solution containing at least one compound from each of at least two of the following three groups: (A) an -aminoacid, -amino acid derivative, aliphatic carboxylic acid, hydroxy oxycarboxylic acid, ketocarboxylic acid, aromatic carboxylic acid, aminocarboxylic acids, quinoline derivative, pyridine derivative, amine or amine derivative, which amine or amine derivative forms a Cu(ll) complex having a stability constant from 5 to 15; (B) a 4-aminophenol or 3-pyrazolidone; and (C) an ascorbic acid derivative of the following formula
wherein R is a hydrogen atom or a hydroxyl group, and n is a positive integer of from 1 to 4, provided that when n = 1, R represents only a hydroxyl group or an alkali metal salt thereof.