The invention relates to a process for the preparation of iminodisuccinic acid ammonium metal salts, characterized in that, in a first stage, maleic anhydride (MA), alkali metal hydroxide and water are mixed in the molar ratio of 2:0-3:5-30 and then ammonia is metered in in the ratio MA:ammonia 2:1.5-8, in order to obtain iminodisuccinic acid ammonium salts which, in a second stage, are reacted with metal oxides, metal hydroxides (and) or other metal salts or their mixtures to give iminodisuccinic acid ammonium metal salts of the formula 8, IDA(NH4)x(Na)y(K)z(Me)m.(NH3)n  Formula 8 in which IDA represents iminodisuccinic acid anion, x=0.1-3.9 y=0-3 z=0-3 m=0.1-2 n=0-6 and Me represents metals of the IInd, IIIrd and IVth main groups and of the Ist to VIIIth subgroups as well as metals of the lanthanide series, of the Periodic Table, which can occur in the oxidation states 1, 2, 3 or 4, the compounds themselves and their intermediates, and the use.