The effects of temperature on a surface plasmon resonance (SPR) sensor in Kretschmann configuration are studied experimentally and theoretically. SPR experiments are carried out over a temperature range of 278-313 K in steps of 5 K. A detailed theoretical model is provided to analyze the variation of performance with varying temperature of the sensing environment. The temperature dependence of the properties of the metal, dielectric, and analyte are studied, respectively. The numerical results indicate that the predictions of the theoretical model are well consistent with the experiment data.