This thesis deals with a methodology for PHP web applications refactoring. The main objective is to propose such a methodology, and to apply it on a real project. The first chapter contains objectives, restrictions and contributions of the thesis. The research of the existing literature on similar topics follows in the second chapter. The third chapter comments on selected software development methodologies' approach to refactoring. The fourth chapter describes known code smells, and adds some new ones appearing particularly in PHP. Specifics of PHP refactoring are also described. The fifth chapter deals with the methodology proposal itself. It sums up requirements, deployment assumptions, the methodology principles and general characterist...