Linear stability of a steady convective motion of a viscous incompressible uid generated by internal heat sources in a tall vertical annulus is investigated. The heat sources are distributed within the uid in accordance with the Arrhenius law. The problem for the determination of base ow in this case is nonlinear. The base ow velocity and temperature distribution is obtained numerically using Matlab. Linear stability of the base ow is investigated with respect to asymmetric perturbations. The stability boundary depends on the two parameters: the Prandtl number and the Frank-Kamenetskii parameter. It is shown that even for small Prandtl numbers (in contrast with the case of uniformly distributed heat sources) marginal stability curves consist of two separate brances. Calculations show that the base ow is destabilized as both parameters (the Prandtl number and the Frank-Kamenetskii parameter) increase.