A simple analytic formula for the spectral radius of matrix continuous refinement operators is established. On the space L m 2 (R s ), m ≥ 1 and s ≥ 1, their spectral radius is equal to the maximal eigenvalue in magnitude of a number matrix, obtained from the dilation matrix M and the matrix function c defining the corresponding refinement operator. A similar representation is valid for the continuous refinement operators considered on spaces L p for p ∈ [1, ∞), p = 2. However, additional restrictions on the kernel c are imposed in this case.