Abstract: This study presents the feasibility of altering the phenol-formaldehyde resins through a modifier increasing their heat resistance. The presence of strong benzene rings that form a networked spatial structure of the polymer is the determining factor of the thermal stability of binders on a fenr base and the stability of the myelene groups. The results have revealed that utilizing resocin produces the intended outcomes concerning maximizing the thermal oxidizing ability of resins. This material is remarkably impervious to thermo-oxidative degradation, additionally, it has two hydroxyl groups. Resocin as a modifier of the heat-resistance-increasing resin binder compositions has proved its efficiency experimentally which focuses our attention on accomplishing thermal stability indicators surpassing furan resins due to the fact that furfuryl alcohol is not one of their components which ensures more health conditions and improved environmental performance in manufacturing large-scale steel casting.