Addressing Quality of Service and specification of quality attributes has been gaining a growing importance in the software engineering area. The research presented in this study investigates different approaches to specification of Quality of Service. UML profile for Quality of Service is one of the standards of the Quality of Service specification and is described in the QoS specification context. The research aim of this thesis is the evaluation of the UML profile for Quality of Service against the following criteria: expressiveness, reusability, understandability, applicability and tool support, as well as further comparison of the profile with other Quality of Service specification languages. To perform that, several tasks and activities were conducted, such as a survey on different QoS specification languages, an examination of the UML profile for Quality of Service, the formulation of the evaluation criteria, and the appliance of the criteria in the evaluation and comparison processes. This study is performed from the perspective of readers and users of the profile that are not UML experts but have sufficient knowledge of UML in terms of software systems analysis and design. The context of the UML profile and Quality of Service aspects include basic concepts of the UML 2.0 and Quality of Service which will be described along the thesis. The main contribution of the thesis is the evaluation of the UML profile for Quality of Service against a set of criteria, followed by explanations on the contents of the profile and how Quality of Service is specified within it. The presented comparison of the UML profile and other Quality of Service specification languages could be the basis for a user to decide what language to use in a particular situation. This study can be comprehended as a starting point for further evaluation of the UML profile and its comparison with other quality specification languages.