[en] A nodal method is developed for the solution of the multigroup neutron-diffusion equation in three-dimensional hexagonal-z geometry. The method employs an extension to hexagonal geometry of the transverse-integration procedure used extensively in the development of nodal schemes in Cartesian geometry. The partially-integrated fluxes in the three hex-plane directions are approximated by a polynomial tailored to the unique properties of the transverse-integrated equations in hexagonal geometry. The final equations, which are cast in the form of local inhomogeneous response matrix equations for each energy group, involve spatial moments of the node-interior flux distribution plus surface-averaged partial currents across the faces of the node