A mathematical computer-aided model CELLOP was constructed in which the desirability functions in a three-dimensional experimental design can be used to find the optimal growing conditions for plant cells. CELLOP is intended for the optimisation of 3 to 6 physical, chemical, or biological variables in the cultivation conditions of plant cell cultures. The model was used to optimise the culturing conditions (calcium, inorganic nitrogen, and sucrose concentrations) for coumarin-producing, spontaneously embryogenic cell lines of angelica Angelica archangelica L. subsp. archangelica and hogs fennel Peucedanum palustre (L.) Moench. For A. archangelica the overall optimum concentrations were 0.47 mM Ca2+, 5.06 mM NO3−, 0.40 mM NH4+, and 96.25 mM sucrose. The dry mass was 24.7 % higher and the coumarin content 40.5 % higher than those achieved in the standard 75 % Gamborg B5 medium. For A. archangelica the highest embryogenic activity was reached in the media containing 1.25 mM Ca2+. In the case of P. palustre the overall optimum concentrations were 1.60 mM Ca2+, 2.84 mM NO3−, 0.23 mM NH4+, and 85.10 mM sucrose. For P. palustre the dry mass production increased by 61.8 % and the coumarin content by 58.1 % compared to the values achieved in the Gamborg B5 medium. For P. palustre the highest embryogenic activity was reached in the presence of 50.0 mM NO3− and 4.01 mM NH4+.