AbstractDeveloping time-critical systems requires expressive, rigorous, easy to use notations to describe the time-related features of the systems, in a way that is formal enough to support and automate activities like property verification and test case generation. We propose a dual-language approach provided with a descriptive formalism for specifying the properties of a system and its components in addition to the typical UML (and UML-RT) diagrams. This description consists of a formula of a new logic, called OTL (Object Temporal Logic), which is an extension of OCL. The approach is applied to a case study derived from the authors' industrial experiences