Electronic Journal of Differential Equations, Vol. 2008(2008), No. 150, pp. 1-12. Title: Dispersive estimates for a linear wave equation with electromagnetic potential Author: Davide Catania (Univ. di Brescia, Italy) Abstract: We consider radial solutions to the Cauchy problem for a linear wave equation with a small short-range electromagnetic potential (depending on space and time) and zero initial data. We present two dispersive estimates that provide, in particular, an optimal decay rate in time $t^{-1}$ for the solution. Also, we apply these estimates to obtain similar results for the linear massless Dirac equation perturbed by a potential. Submitted December 12, 2006. Published October 29, 2008. Math Subject Classifications: 35A08, 35L05, 35L15, 58J37, 58J45. Key Words: Wave equation; electromagnetic potential; short-range; Dirac equation; dispersive estimate; decay estimate.