A process for continuous production of ammonium thiosulphate, (NH.sub.4).sub.2S.sub.2O.sub.3 (ATS) from NH.sub.3, H.sub.2S and SO.sub.2 is disclosed. A first feed stream comprising H.sub.2O, H.sub.2S and NH.sub.3 with a molar H.sub.2S:NH.sub.3 ratio <0.4 is partially condensed to form a condensate. The condensate is contacted with a third feed gas comprising H.sub.2S and the gas stream comprising NH.sub.3 and H.sub.2S is passed to a mixing device where the gas stream is dissolved in water drained off from an aerosol filter. A second feed gas stream comprising approximately 2/3 mole SO.sub.2 per mole of NH.sub.3 contained in the first feed stream is passed to a SO.sub.2 absorber. The aqueous solution produced in mixing device is contacted with the SO.sub.2 absorber.