NOVELTY - A bath (B1) for electroplating I-III-VI compound comprises water; copper containing precursor dissolved in water; selenium containing precursor dissolved in water; and at least one member selected from indium containing precursor and/or gallium containing precursor dissolved in water; and at least one member selected from sulfur-containing organic compound dissolved in water, where at least one sulfur atom directly bond with at least one carbon atom, and/or phosphorus-containing organic compound dissolved in water, where phosphorus atom directly bond with at least one carbon atom.    USE - As bath for electroplating I-III-VI compound; for producing I-III-VI compound in thin film form by electroplating (claimed); and as light absorbing layer in solar cells for converting light energy into electrical energy.    ADVANTAGE - The bath exhibits improved solution properties and stability for the deposition of Group I-III-VI films. The method allows a better control of the film quality and composition.    DETAILED DESCRIPTION - A bath (B1) for electroplating I-III-VI compound comprises water; copper containing precursor dissolved in water; selenium containing precursor dissolved in water; and at least one member selected from indium containing precursor dissolved in water and/or gallium containing precursor dissolved in water; and at least one member selected from sulfur-containing organic compound dissolved in water, where at least one sulfur atom directly bond with at least one carbon atom, and/or a phosphorus-containing organic compound dissolved in the water, where at least one phosphorus atom directly bond with at least one carbon atom. An INDEPENDENT CLAIM is included for method of producing I-III-VI compound in thin film form by electroplating, involving obtaining a bath comprising water, copper containing precursor dissolved in water, selenium containing precursor dissolved in water, and at least one member selected from indium containing precursor dissolved in water, and/or gallium containing precursor dissolved in water, and at least one member selected from sulfur-containing organic compound dissolved in water, where at least one sulfur atom directly bond with carbon atom, and/or a phosphorus-containing organic compound dissolved in water, where at least one phosphorus atom directly bond with carbon atom; immersing a cathode and an anode into the solution; and applying electric current or potential across the cathode and anode to deposit film of I-III-VI compounds on the cathode.