Abstract 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. Acoustic emission signals produced during machining were analyzed. The signals provided a clear picture of the status of the tool and nature of cutting of the work piece. The study revealed the existence of a critical speed of machining. A critical range of temperature also has been identified at which the specific cutting pressure is almost steady. Modeling of temperature using multiple regression analysis was carried out for precise prediction of temperature and control of machining parameters if necessary during machining. Range of effective hardness for the tool has been identified for machining.