Ramanujan's Master theorem states that, under suitable conditions, the Mellin
transform of a power series provides an interpolation formula for the
coefficients of this series. Based on the duality of Riemannian symmetric
spaces of compact and noncompact type inside a common complexification, we
prove an analogue of Ramanujan's Master Theorem for the spherical Fourier
transform of a spherical Fourier series. This extend the results proven by
Bertram for Riemannian symmetric spaces of rank-one.