The invention herein disclosed comprises the use of oxazolidines, nitroalcohols, nitrones, halonitroparaffins, oxazines, azaadamantanes, hexamethylenetetramine salts, nitroamines, imidazolidines, triazines, nitrooxazolidines, and imidazolidine-oxazolidine hybrids to serve as hardeners for curing phenolic resins. The hardeners and accelerators/catalysts described in the invention can be applied in any application where phenolic resins are used, including but not limited to fiber reinforced composite applications such as pultrusion, filament winding, bulk molding compound (BMC), sheet molding compounds (SMC), vacuum assisted resin transfer, prepregs, adhesives, foundry materials, abrasives, friction materials, insulation, laminates, coatings, electronics, fire resistant, and flame-retardant end uses.