Police work is a stressful occupation, where officers are exposed to chronic and intense stressors. When it comes to understanding and predicting reaction to prolonged stress, it has been shown that there is more to personality than what can be captured by the most widespread personality models. Adding Mental Toughness as the capacity to tolerate and overcome stress at work, as well as the Dark Triad as a tendency for malevolent behaviour, to the traditional model of assessing the personality of a police officer can improve the prediction of important outcomes. The aim of this paper was to examine the psychometric properties of the Serbian translations for the Mental Toughness Inventory (MTI) and the Dark Triad Dirty Dozen (DTDD) in a population of police students. The research was conducted on a sample of 92 students in their first and second years at the University of Criminal Investigation and Police Studies. Considering the specificity of the sample, both instruments showed good reliability (Cronbach's Alpha Based on Standardized Item a = 0.81 for MTI and a = 0.84 for DDTD); factor structure was confirmed for the MTI (ch² = 51.5, p < 0.001, CFI = 0.864) and DTDD (ch² = 105, p < 0.001, CFI = 0.886) as well as convergent (r=-.384, p < 0.01 between Mental toughness, and Machiavellianism). Although deviations from the normal distribution were obtained, having in mind the rigor of psychological and physical selection into the Police University, the obtained psychometric properties of the MTI and DTDD were acceptable and we recommend the instruments for further usage.