I am working on my thesis that concerns the leadership styles and employees performance, can anyone suggest any questionnaire to measure transformational and transactional leadership styles as well as employees performance?
Have a look at the free LeaderShaper app on Apple or Android. It is a self assessment tool for emotional intelligence but for about US$4 you can get a report that provides competence is six leadership styles. If this shows promise then you can move on to look at LEIPA, https://www.leadershapeglobal.com/leipa a unique 360 tool that compares "competence" with "importance in role" of six leadership styles (four are transformational, two are transactional.
Muenjohn, N., & Armstrong, A. (2008). Evaluating the structural validity of the multifactor leadership questionnaire (MLQ), capturing the leadership factors of transformational-transactional leadership. Contemporary management research, 4(1).
Procházka, J., Vaculík, M., & Smutny, P. (2016). Czech Leadership Questionnaire: The Development of a Czech Questionnaire of Transformational and Transactional Leadership. Proceedings of Hradec Economic Days 2016.