Payment for Environmental Services (PES) can be defined as a monetary/non-monetary compensation mechanism (provider-receiver principle) by the supply of environmental services. This work identified and analysed Brazilian and Argentine PES’s case studies under a national perspective but also under an eventual and future River Plate watershed. Brazilian projects can be considered unique due their special conditions and the environmental goals of the various Federative Entities, mainly the case of Sao Paulo state. In Argentina, by contrast, and despite improvements in PES projects through county and federal government initiatives. Finally, it was suggested some aspects that could be utilized, such as “parameters”, to promote social, economic, and environmental standardization in conjunction with regional PES projects that require international cooperation.