The establishment of sustainable leadership is essential for the process of implementing reforms in public sector. Sustainable leadership implies effective leadership capable of responding to changes that come from both the internal and external environment. To achieve this, it is necessary to apply multi-criteria decision-making methods. In this paper, the new multi-criteria decision-making method PIPRECIA was used to assess the criteria and five models of leader behaviour that are significant for the process of implementing reforms in the public sector of the Republic of Serbia. In essence, the paper aims to emphasise the simplicity of the practical application of the PIPRECIA method, which was discussed through a numerical illustration on the basis of which the conclusions were drawn. The research results indicate that the criterion Individual competence of the leader (C4-0.24) has the greatest weight. By ranking the alternatives, it was estimated that the Charismatic model of behaviour (A5-0.219) is the leader’s behaviour model that can have the greatest importance in the process of implementing public sector reforms. The Directive model of behaviour (A3-0.197) was derived as the second most important, which is understandable if we consider the fact that this model of leader’s behaviour traditionally dominates the work of the public sector. Furthermore, Participatory behaviour model (A1-0.193), Supportive behaviour model (A2-0.193) and Transformational behaviour model (A4-0.193) have equal rank, which means that they have the same importance for the decision-maker. The findings provide significant information to leaders of public organisations on how to implement reforms and manage human resources more effectively.