In the present work, the environmental damage of two types of molten salts and synthetic oil has been evaluated with the aim of deciding whether the use of molten salts is more suitable than synthetic oil from an environmental point of view. To this end Life Cycle Assessment has been used, since it offers numerous advantages in the assessment of aspects associated with the development of a product and its potential impact throughout the life of a given product from raw material acquisition, processing, manufacturing, use and finally its disposal. According to the results, the replacement of the VP-1 like thermal oil by molten salts is absolutely recommended from an environmental perspective, since the environmental impact of molten salts appear to be reduced in comparison to Therminol®VP-1. Thus, direct systems, in which thermal storage and heat transfer fluid are unified using molten salts, emerge to improve the power cycle performance, these being a good option not only from the known technical point of view, but also from the environmental point of view. Life Cycle Assessment seems to be a suitable and necessary methodology to quantify the environmental impacts of fluids, materials, and O&M in CSP plants.