  Let G be a binary tree with vertices V and let H be a Schroedinger operator
acting on l^{2}(V). A decomposition of the space l^{2}(V) into invariant
subspaces is exhibited yielding a conjugate operator A, for use in the Mourre
estimate. We show that for potentials q satisfying a first order difference
decay condition, a Mourre estimate for H holds.
