The rate coefficient for energy-pooling collision Rb(5P)+Cs(5D)→Rb(5S)+Cs(8D) in the Rb-Cs vapor mixture has been measured using a known energy-pooling rate coefficient of a homonuclear reaction [ie.,Cs(6P)+Cs(5D)→Cs(6S)+Cs(7D J)]. Populations of the Cs(6P,5D) arid Rb(5P) states have been produced by photodissociation of Rbj and 0? molecules by the use of a dye laser radiation. The resulting fluorescence includs the components emitted in the decay of the exited states produced by photodissociation and the components arised from the collisionally populated excitation-states. By combining relative intensities of the components with Cs(6P), Rb(5P) states effective lifetimes, the rate coefficient for the heteronuclear energy-pooling is obtained to be cm3/s. The contribution to the rate coefficient from other processes is discussed.