Abstract. This paper proposes an inductive method to construct bases for spaces of spherical harmonics over the unit sphere Ω2q of C q . The bases are shown to have many interesting properties, among them orthogonality with respect to the inner product of L 2 (Ω2q). As a bypass, we study the inner product [f, g] = f (D)(g(z))(0) over the space P(C q ) of polynomials in the variables z, z ∈ C q , in which f (D) is the differential operator with symbol f (z). On the spaces of spherical harmonics, it is shown that the inner product [·, ·] reduces to a multiple of the L 2 (Ω2q) inner product. Bi-orthogonality in (P(C q ), [·, ·]) is fully investigated.