The work studies the transition from periodic to chaotic oscillations in a dc-driven planar gas discharge with a high-ohmic electrode. The applied voltage and resistance of the semiconductor layer act as control parameters. The oscillations occur in the subnormal discharge regime. The bifurcation diagram and Lorenz map characterizing transition of this system to chaos through period-doubling bifurcations are obtained. Numerical models employed are based on the drift-diffusion theory of gas discharges. The effect of two modelling approaches, namely the 'simple' fluid model and the more detailed 'extended' fluid model, is considered. The calculations showed that the results obtained by these two approaches are different in quantitative terms, however, qualitatively similar in terms of the dynamic behavior of the system as a function of the control parameters.