A multi-stage, superheated steam generator for crude oil recovery comprises a plurality of radially spaced-apart first stage electric heating tanks that peripherally surround an inner, second stage electric steam tank. The steam tanks are secured within casing by a slack accommodating mounting comprising a downwardly projecting stub received within a rigid, tubular expansion sockets secured beneath each steam tank. A plurality of serpentine, electric resistive heating elements abut each steam tank. The elements have loop portions proximate the bottoms of each steam tank and vertical portions abutting each tank periphery. First stage tanks output steam to a manifold system that outputs to the second stage heater.