This work is about the possibilities of use of the in-stream or river hydrokinetic devices and their development in Latvia and the world, as well as evaluation of the potential of their use and their further development. There are previous achievements in river hydrokinetic devices systematized and analysed in the review of literature. Specifics of the use of those devices for electricity generation are reviewed. Analysis performed for the methods that has been used for evaluation of the amount of electricity attainable by hydrokinetic devices from a specific river, a part of a river or a whole region of rivers. A new evaluation methodology is developed in this work that is tailored to the local circumstances and resources and is based on performing measurements in the river. The methodology allows to evaluate potential for electricity production using hydrokinetic devices for any river in which it is possible to travel and stand relatively still with any floating means. Potential for electricity production in using hydrokinetic devices were evaluated for extensive areas of the lower Daugava (from Līvāni to Jaunjelgava) by try out and use of this methodology. Influence of different variables and restrictions to the results of evaluation and relation between flow velocity and cross-section area are researched during those evaluations. Use of the channelling devices together with hydrokinetic devices is analysed as well. A methodology for the evaluation of the efficiency of the channelling devices is developed and results with it obtained for the same areas of the river Daugava. Research is performed regarding development of both hydrokinetic devices and channelling devices together with them. The results of the work are used for preparation of nine patent applications that are mainly new hydrokinetic device and their channelling device constructions or parts of those. A modelling tool is developed which uses data acquired according to the methodologies as input and allows to plan HKD placement in the river and anticipated economical gains. In each chapter experience is analysed and conclusions made regarding corresponding part of the work. Main conclusions are gathered and analysed in the end of the work.