Title: Hartley-Bessel-Boas's Theorem Prof: Radouan DAHER University Hassan 2 Casablanca Morocco Abstract: Using some preliminaries of the Hartley-Bessel harmonic Analysis ,we establish an analog of the classical Boas-Moricz's theorem for Hartley -Bessel transform . Joint work with M.A. Chenna, S.L. Hamad M.El Hamma-L.Rakhimi.