Electrokinetics can be utilized to solve many problems in geotechnical and environmental engineering. The processes which occur in association with electrokinetics are complicated and difficult to control. The success of the application depends on certain conditions which are controlled by many parameters. It is therefore important to understand these processes so that methods and procedures can be optimized. In this paper theoretical considerations, results of tests and examples of in situ applications are presented and discussed. The presented examples show ways of controlling and improving the efficiency of electrokinetic processes.