This paper addresses the problem of expressing preferences among non-functional properties of services in a Web service architecture. In such a context, semantic and non-functional annotations are required on service declarations and business process calls to services in order to select the best available service for each invoca-tion. To cope with these multi-criteria decision problems, conditional and unconditional preferences are managed using a new variant of conditional preference networks (CP-nets), taking into account uncertainty related to the preferences to achieve a better satisfaction rate. This variant, called LCP-nets, uses fuzzy linguistic information inside the whole process, from preference elicitation to outcome query computation, a qualitative approach that is more suitable to business process programmers. Indeed, in LCP-nets, preference variables and utilities take linguistic values while conditional preference tables are considered as fuzzy rules which interdependencies may be complex. The expressiveness of the graphical model underlying CP-nets provides for solutions to gather all the preferences under uncertainty and to tackle interdependency problems. LCP-nets are applied to the problem of selecting the best service among a set of offers , given their dynamic non-functional properties. The implementation of LCP-nets is presented step-by-step through a real world example.