Glass fiber reinforced polymer (GFRP) bars are currently used as internal reinforcement of concrete structures, as an alternative to traditional steel rebars, to avoid corrosion problems and durability issues. GFRP bars are usually made of continuous glass filaments embedded within a polyester (for non-structural applications) or vinyl ester resin. These resins have been used for many years in several technological fields and widely employed as matrices for composite materials with structural functions. However, since the matrix plays a fundamental role in protecting the fibers from the external environment, the development of new organic matrices able to withstand aggressive environmental conditions while keeping a low cost of production is certainly of great interest. In this study, the possibility of using a modified acrylic resin (ModAR), never employed for such applications, as matrix for GFRP bars has been investigated. Physical, mechanical and durability tests have been carried out, according to international standards, to evaluate the technical feasibility of using ModAR matrices. Experimental results showed that ModAR GFRP bars are able to offer high thermal resistance while keeping physical and mechanical properties within standard limits.