Total/occluded or residual gas content of sintered nuclear fuel pellets is an important specification. The specification of the gas content depends on the nature of the fuel and type of the reactor. The total gas content and its composition were determined employing hot vacuum extraction followed by quadrupole mass spectromety. Detailed investigations carried out on the determination of total gas in various types of nuclear fuels used in different types of reactors are reported in this paper. Oxide pellet is heated at 1650degreesC for 15 min while carbide pellet is heated at 1000degreesC for 30 min for the determination of total gas content. The overall measurement error is +/-5% and the detection limit is 0.005 cc. The main constituent of the gas is hydrogen (> 95%) in all the types of fuel, pellets.