The invention relates to a pyrolysis process carried out in the presence of a controlled carbon dioxide environment that allows recovering both the organic portion and the inorganic portion (glass fibers) of a fiberglass-reinforced plastic waste, at an organic yield recovered even higher than 95% by weight and with a suitable for manufacturing new articles, in particular fiberglass-reinforced plastic articles, which provides a profitable to the disposal in dump areas. In particular, the recovered organic products can be mixed as such, at a percentage as high as 20% and more, with a fresh unsaturated polyester resins that is normally used to manufacture common fiberglass-reinforced plastic articles, without worsening its features with respect to articles made starting from fresh resin alone. The glass fibers, which are fully recovered in a combustion treatment after the pyrolysis, are reused fully replacing the corresponding virgin glass fibers, since they are unbroken and perfectly clean in a final step of the process.