This paper presents the effect of temperature on the natural frequency of (1,1) mode shape of a Resonant MEMS IR bolometer pixel in the range of 295-340 K. The detector pixel has a square plate geometry having side length of 1400μm and thickness of 35μm. The resonating plate is supported at its geometric center, enabling more robust pixels with fill factor greater than 90% and less complicated fabrication process. The sensor is fabricated using a Silicon-On-Glass (SOG) process. For the first time in the literature, the closed form equation to calculate the natural frequency of the fundamental mode shape of a MEMS square plate as a function of temperature change is derived for the single crystal silicon as the structural material. FEM simulations and experiments are conducted to verify the analytical model. For the electromechanical response characterization of the pixel structure, frequency response and system level temperature tests are conducted. Fundamental natural frequency shift is also tested during the frequency response tests for the same temperature range and the scale factor of the fabricated sensor is measured to be 1.90Hz/K for mode shape (1,1).