Topological algebras with
Schauder orthogonal bases are studied. Radicals, closed ideals and closed maximal
ideals of such algebras are described. It turns out that a locally m-convex algebra
with identity and having an orthogonal basis is metrizable. This implies that a
complete locally m-convex algebra with an orthogonal basis and identity is
algebraically and topologically isomorphic with the Fréchet algebra of all complex
sequences.