Modularized, superheated steam generators comprise a steam module (46), a thermocouple module (41), and an electrode module (45) assembled within a containment enclosure (66). The multi-stage steam module (46) comprises a plurality of first stage pressure vessels (77) surrounding and feeding a second stage pressure vessel (78). The steam module (46) is coaxially surrounded by insulation (48) disposed within a cylindrical shroud (72). The electrode module (45) radiantly heats the steam module with resistive heating elements (119). The thermocouple module (41) includes thermocouples monitoring first stage temperatures within and between pressure vessels (77). PLC computer SCADA software (600) operates the generators. Thermocouple data is analyzed to control heater temperatures, the water feeding system (340), and outputted steam temperature. PLC software (600) provides operating logic (602) establishing a start up subroutine (602), a ramp up subroutine (603), a steady state subroutine (605), and a shut down subroutine (606).