The scientific aim of research activities is to promote scientific discussion and in-depth research of aspects related to certification of persons in order to identify whether the certification process as a conformity assessment procedure contains formal attestation of conformity or it ensures compliance of professional competence in accordance with the requirements set out in the professional sphere. Several research methods, such as literature review, logical and comparative analysis and survey analysis are applied in this research. The analysis was carried out by collecting qualitative and quantitative data while studying and evaluating the concept of certification and the main elements of professional competence, at the same time defining the activities to be carried out within the framework of the research. Competence evaluation is the biggest challenge at present. Certification of persons is associated with professional competence and conformity assessment activities and it is one of the most common ways of evaluating professional competence that can be used to assess the professional competence if explicit competences in the particular sphere for the person are defined. Due to the fact that in the certification process of persons the achievement and measurement of competences are not typically standardized and clearly defined, professional competence assessment in the certification process does not represent the demonstration of the ability to apply knowledge and skills and to display personal characteristics according to the certification schema defined in ISO 17024. Evaluation and analysis of the theoretical aspects of certification of persons provide a general notion of certification as the conformity assessment procedure which applies to any area to be certified and can serve as a basis for further studies of certification. Bodies operating certification of persons should evaluate not only the knowledge of the persons to be certified and their professional experience in the particular sphere, but also their ability to apply the acquired knowledge and skills in situations related to their professional activities, i.e. their competence.