Abstract <p>A new method for the determination of water-soluble carbohydrates (glucose and fructose) using cross-linked polyvinyl alcohol–magnetite sensing composite films was developed. A digital image colorimetry technique with image processing in the RGB space was proposed for recording the analytical response of the sensing films. The water-soluble carbohydrates were determined in a phosphate borate buffer solution at pH of 8.5 and at a sodium tetraborate concentration of 0.05 moL/L. The film impregnated with a solution of iron salts for 2 min prior to precipitation of Fe₃O₄ particles proved to be most sensitive. The limit of detection of glucose and fructose in aqueous solutions was 11 mmol/L. The proposed approach was tested in analysis of natural monofloral honey samples. This method for determination of glucose and fructose does not require special laboratory equipment to measure the analytical response and can serve as an alternative to the photometric ferricyanide method for glucose and fructose determination.</p>