Abstract: The relevance of this study is that R&D and application of ultralight composite cylinders based on polymer liners in place of metal and metal-composite pressure cylinders based on metal liners hold much promise. This study sought to theoretically and experimentally investigate the rotational molding process for polymer liner to be used in composite pressure cylinders. A mathematical description of the rotational molding of plastics was considered and allows the optimum rotational speed of principal and central axes to be identified. Literature recommendations on rotational speeds for items of different shape are given. A rotational molding device was designed and experiments were done to examine how the heating, residence and rotational speed regimes influence the resultant items’ characteristics. Rotational molding regimes (30 min residence time at 200-205 ºС) were experimentally found for Lotte UR-644 (LLDPE) fine polyethylene. The best equithickness value for items (with a 1.5 mm thickness deviation) was obtained at a rational speed ratio of the principal and central axes of 2:1.