This paper deals with the measurement of transient exhaust gas velocity and temperature simultaneously under motoring and firing conditions in an internal combustion engine, using a new ultrasonic velocity temperature meter. The performance of the ultrasonic meter was compared with the well known spark discharge velocity meter and the wire resistance thermometer, under dynamic conditions. The experimental results presented here were used to substantiate the mathematical model evolved for studying gas exchange processes in internal combustion engines. Copyright © 1980 Society of Automotive Engineers, Inc.