The efficiency of the electrohydrodynamic (EHD) cooling and thermostating systems of electronic and electrical devices is investigated. A design of electroconvective cooling of an X-ray generator is proposed, the effectiveness of which is confirmed on laboratory models and full-scale samples. The anode temperature was reduced by a factor of two, the duration of the emitter operation increased, and the reliability of the device improved. Various methods of cooling a high-voltage transformer are presented allowing one to increase the specific power, to reduce the weight and size parameters and the temperature of the coolant, and to augment the resource. Studies have been conducted to establish the possibility of thermostating the heat-emitting element (block) by EHD methods when both external and internal conditions change. The design of an EHD thermostat with an automatic thermal stabilization system has been developed and tested (the temperature is maintained with an accuracy of ±0.05°С). A frame with an EHD liquid circuit and an EHD thermostat has been designed, which allows one to significantly reduce the longitudinal temperature differences and its deformation. The high efficiency of EHD cooling methods is shown by an example of a block of light-emitting diodes, small elements and components of electronic equipment, and the use of electrodes—wires with a perforated insulating coating when cooling flat heat-emitting surfaces; a sevenfold increase in the heat-transfer coefficient is achieved.