Employee performance assessment is a complex process which aims to identify the effectiveness of the staff's daily activity and to provide information that will help in decisionmaking. In this article, employee performance is viewed as a complex structure which is comprised of four criteria groups (qualification, staff morale, productivity, discipline). In its turn, each criterion is comprised of sub-criteria. We have developed an adaptable assessment structure that can be easily adjusted to the specific nature of any enterprise. We have used a convolution method to combine criteria into a generalized parameter. We suggest a methodology for employee performance assessment as well as an automated program. The suggested convolution of the staff performance criteria can be used in the systems for optimization and decision-making. 1. Introduction Regular employee performance assessment is the basis of effective managerial decision making which is crucial for increasing the productivity of an enterprise. Usually, the performance is represented through numbers: the relation of the profit of some production element to the cost of its implementation [1], [2], [3]. This approach cannot really be used to assess employee performance since it does not reflect many significant factors (the stage in the life cycle of the enterprise, the employee's unit type, etc.). Nowadays, there is a shift of approach to the employee performance evaluation in Russian companies. A distinct characteristic of this process is the implementation of various methods which are aimed at assessing the conformity with multiple indicators and criteria. However, evaluation techniques, which are widely used abroad, have been implemented in Russia only recently. Neither in Russia, nor abroad is there a unified system for solving any occurring problem. Various authors address the issue of employee performance assessment in their works [4], [5], [6], [7], [8], [9], [10], [11]. Some works deal with employee performance evaluation in narrow specializations; for example, in health care system [12], construction industry [13], processing industry [14], and even in football [15]. In this work, we suggest a methodology for employee performance assessment at a random enterprise. We address employee performance as a complex structure which consists of four criteria groups (qualification, staff morale, productivity, discipline), where each criterion is comprised of subcriteria. We have used a convolution method in order to compile criteria into a generalized parameter. We suggest a methodology employee performance assessment based on criteria convolution with the help of the Kolmogorov-Nagumo average. We have also developed a related automated programhese guidelines, written in the style of a submission to J. Phys.: Conf. Ser., show the best layout for your