Phenyl ethynyl functional addition curable phenolic resins were synthesised by reacting a mixture of phenol and 3-(phenylethynyl) phenol (PEP) with formaldehyde in presence of an acid catalyst. Relatively narrow molar-mass distributed polymers were obtained in good yield. The presence of PEP led to reduced molar-mass and narrow distribution of the copolymers. The resin underwent thermal curing at around 250-275 degreesC, much lower than the cure temperature of PEP. The thermal stability and anaerobic char residue of the cured resins increased with increase in ethynyl-content and these properties were more than those of resol resin. These addition cure phenolics provided an overall increase in char of about 70% vis-a-vis resol resin when compared on the basis of uncured resins.