The highlights of this article are the problems of critical thinking development while teaching English to the students of technical studies. The main concern is the involvement of the students in the process of working under such project tasks as web quests. Specifically, student's participation in the studying of professional foreign language (ESP) is described. Particular attention is paid to the role of a web quest in increasing the students’ motivation and stimulating their cognitive activity in professional foreign language (ESP) learning. The article also deals with the problem of critical thinking evaluation in the process of implementation of project activities, the basic conclusions on this issue are formulated and the parameters of evaluation system are presented