The dynamics model for fast transients analysis in the Polish research reactor Maria has been developed. The model includes, besides the point kinetic equations, the heat transfer and spatially dependent equations for calculating the temperature distribution in the average fuel channel. The space effects in the reactor core were taken into account by flux-weighted temperatures. The code TOTEM, for the CDC-CYBER 73 digital computer, was written in FORTRAN-EXTENDED. Detailed calculations allowed us to obtain the following dynamics parameters for the hot and poisoned reactor core: βeff = 0.00726 and l = 2.65 × 10−4 s. The temperature-dependent reactivity coefficients were used to calculate the feedback effects. To examine the applicability of the model, a series of rod drop experiments was performed, and the comparison of the calculated and measured excess reactivities has shown that the discrepancy does not exceed 2%.