The characteristics of electroconvection and electroconvective heat transfer in liquid dielectrics possessing unipolar injection conductivity [1, 2] are investigated and certain types of EHD pumps are calculated. These investigations are necessary because so far there is no theoretical explanation for the slowing of heat transfer with increase in voltage in strong fields [3, 4]. Moreover, there is no satisfactory theory of EHD pumps that would make it possible not only to establish the basic operating principles of existing (grid [5], knife-edge [6] and other [7, 8]) equipment but also to predict the performance of high-pressure EHD pumps.