The development of open-source applications in the nuclear field has recently attracted interest from the scientific community, due to the potential mutual support useful both in the research field and in the analysis of new nuclear reactor concepts. This kind of tool allows developers to adapt the code according to their own needs, which is not generally feasible with proprietary software, designed for traditional commercial reactors and used as a black-box from the user’s point of view. In this framework, the OpenMC neutronic simulation tool, based on the Monte Carlo method and implemented in the accessible and easy-to-learn Python language, provides a wide range of computational capabilities, including fixed source, criticality, and burnup simulations. Verifying the reliability of open source software requires comparison processes with other already existing codes, as well as benchmarks with measurement campaigns. The TRIGA Mark II research reactor is primarily used for neutron activation analysis, education and training, making it an extensive tool for the benchmark of numerical models due to the large amount of available experimental data collected in the past years by Politecnico di Milano. In this paper, the OpenMC model validation of the current configuration of the reactor TRIGA Mark II is proposed by first comparing the control rod worth values of the three reactor control rods (REG, TRANS, SHIM); then, the experimental calibration curves of the three rods were compared with both the OpenMC and the SERPENT predictions, taking into account both the statistical error and the measurement uncertainty, aiming to demonstrate the reliability of the OpenMC code on a real reactor test-case in comparison to the widely-used SERPENT software.