When we develop a software project of a certain complexity, source code maintainability could become a problem, in particular if developers do not use a consolidate development process that simplifies the management of the entire project. When source code becomes very complex, it is difficult for developers to share and modify it. We can improve internal software qualities such as reusability, maintainability and readability through refactoring. Refactoring can be applied to remove possible problems in the code, as code smells. Identifying code smells and removing them through refactoring results in better code maintainability, but it can be an overwhelming task. In this paper, we describe our experimentation on using four refactoring tools to remove code smells in four systems, with the aim to outline advantages and disadvantages of the tools with respect to the accomplishment of this task, and to identify the smells easier to be removed among the ones we considered in this paper.