The efficiency of reactive dyes adsorption onto chitin under dynamic conditions was determined. The research was carried out in an air-lift reactor. A reactive dye with chlorotriazine moiety - Black DN was reactor. A reactive dye with chlorotriazine moiety - Black DN was used. The effect of inlet Black DN concentration, chitin concentration in the reactor and flow rate on the maximum adsorption capacity of chitin under dynamic conditions, on the utilisation of the adsorption capacity of chitin and on the real working time of the reactor were investigated. The results showed that the maximum adsorption capacity of chitin was affected most by inlet dye concentration. The utilisation of the adsorption capacity of chitin, at the assumed effectiveness of dye removal, depended on inlet dye concentration and chitin concentration in the reactor. The highest efficiency was obtained at the chitin concentration in the reactor of 5 g/dm³, inlet dye concentration of 100 mg/dm³ and flow rate of 0.1 V/h.