Local softening or melting of growing polymer particles in fluidized bed reactors may lead to formation of sheets, which require reactor shutdown. The kinetic properties of metallocene catalysts can be modified by alteration of the substituents on the cyclopentadienyl rings. A kinetic model which accounts for the initiation, propagation, and deactivation reactions is used to predict the impact of the kinetic parameters, catalyst properties, and residence time in the reactor on the maximum productivity attained while preventing particle overheating. The maximum productivity decreases with an increase of the deactivation reaction modulus, phi(d), and is an increasing function of the propagation reaction, phi(p). The value of phi(p) depends on both the propagation rate constant and the catalyst loading. The residence time at which the maximum productivity is attained, t(m), depends most strongly on the inoduli for the initiation reaction (phi(i)) and the deactivation reaction (phi(d)). The maximum productivity is rather insensitive to an increase of the residence time above t(m).