The objective of this research work is to understand the impact of soiling on the thermal performance, electrical production and Levelized Cost of Electricity of possible Concentrating Solar Power plants in both Morocco and Portugal. For this matter, a joint soiling measurement campaign, following the same protocol, has been conducted in the two countries to assess and evaluate the impact of dust on the optical properties of soiled solar mirrors. After that, and using high-quality irradiation data measured at ground level, simulation of a 3.6 MWth molten-salt test facility has been conducted with and without taking soiling into consideration for both sites. Results show that soiling in Morocco is three times higher than in Portugal. The daily Soiling rate average is around 1.6% and 0.06% for both sites, respectively. In addition, results show that both sites are favorable for CSP implementation. The simulated electrical output for a clean field is similar to 1.4 GWeh and similar to 1.3GWeh with a Levelized Cost of Electricity of similar to 0.194(sic)/kWh and similar to 0.205(sic)/kWh for Morocco and Portugal, respectively. Nevertheless, when soiling is taken into consideration both sites produce similar amount of electricity of similar to 1.25GWeh with a similar Levelized Cost of Electricity of similar to 0.231(sic)/kWh. (C) 2020 Elsevier Ltd. All rights reserved.