A simple and general scale-up procedure, based on boundary and temperature diagram safety criteria for exothermic semibatch reactors (SBRs), has been developed. Such a procedure is based on a few graphical correlations that allow end users, dealing with homogeneous as well as heterogeneous SBRs (with or without autocatalytic behavior), an easy selection of safe operating conditions at the laboratory scale and for their scale-up to the industrial one, maximizing at the same time the industrial reactor productivity.