The study starts from a hypothesis on the coherence and compatibility of the legal instruments in force in Cameroon and in the Democratic Republic of Congo (DRC) with the optimization of payment for environmental services (PES) and the preservation of environmental services. This study has employed a legal approach and interviews in order to investigate whether there is coherence and compatibility or not between the two variables of this hypothesis: (1) the legal instruments in force in Cameroon and in the DRC and (2) the optimization of PES and the preservation of environmental services. This study consists of three parts. The first part deals with the theoretical framework of PES and the place of PES in the legal order. In this first part, the definition of an optimal PES, the indicators of an optimal PES and the categories of legal frameworks on PES have been revealed. These are the fundamental elements to conduct a systematic analysis in the second and third parts. Based on these fundamental elements, the study analyses the legal instru- ments from international, regional (Africa) and domestic (Cameroon and the DRC) levels and investigates through field research two PES projects, one in Cameroon called “PES comminatory project” and another in the DRC called “REDD CBFF-Luki” respectively in the second and the third parts. From the analysis of these legal instruments and the investigation of these two PES projects, it has become apparent that there is a lack of coherence and compatibility between the legal instruments and these two PES projects in Cameroon and in the DRC, and the optimization of PES and the preservation of environmental services in the Congo Basin in general, especially in these two States. Useful recommendations have been made to eradicate these shortcomings.

Key words: payment for environmental services, environmental services, Congo Basin