Carbon/phenolic composites are used in high performance applications because of their high temperature resistant properties. Studies on the machining aspects of these composites are very few. This paper presents an investigation on machining of this composite material using PCBN tools. The studies on specific cutting pressure revealed a critical speed of machining at which the specific cutting pressure is minimum. A critical range of temperature has been identified at which the specific cutting pressure is almost steady. Range of effective hardness for the tool has been identified for machining.