2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/13410We derive here the expression for the accretion luminosity, $L(\infty)$, as seen by a distant inertial observer $S_\infty$, for the case of spherical accretion onto a static compact object having a surface gravitational red-shift $z_x$. It is found that the ``efficiency'' for conversion of mass energy into accretion energy is given by $ε= z_x/(1+z_x)$. And since the maximum value of $z_x$ permitted by General Theory of Relativity (GTR) is 2, the maximum theoretical value of the accretion efficiency is 66.66%.4 pages using revtex, submitted to Annals of PhysicsAstrophysicsGeneral Relativity and Quantum Cosmologytext