Over the past decade Off-Road emissions legislation framework becomes more stringent. For this reason, OEMs decided to radically change their internal combustion engines, by adopting new technologies able to reduce pollutant emissions. The core of the work is focused on the description of the Closed Loop electronic control of a SCR (Selective Catalytic Reduction) system based on NH3 storage model and its calibration procedure. NH3 storage tests have been carried out on a real test bench with the aim of characterizing the SCR storage capacity as a function of Space Velocity and SCR inlet temperature. SynGas tests results have been taken as a reference.