An architectural panel assembly for mounting a plurality of panel sections to a structural support member. The assembly includes a mounting bracket fixed along a longitudinal edge of one panel section and fixed to the support member. A fastening bracket is fixed along the edge of another panel section. One of the two brackets has a recess and the other a projection for being received and hooked within the recess. By this structure the two panel sections are connected together and are fixed to the support structure in an easy-to-use process.