The document presents the common protocol chosen by the Med-CORDEX modelling community for the so-called Baseline runs performed with coupled regional climate system models. The simulations produced will be part of the phase 3 of the Med-CORDEX initiative that corresponds to CORDEX-CMIP6 international framework. The goals of the current document are to - present the main scientific objectives targeted by these baseline runs - recall the process leading to the chosen common protocol - describe the agreed common protocol for the simulations (evaluation runs and scenario runs) However, this document does not list the participating institutes, models and simulations and does not include the data request and the description of the file naming. Those information are available aside (https://www.medcordex.eu/simulations-phase3.php). This document constitutes the first version of the common protocol and will evolve in the coming months