The article presents a novel control-flow based test sequence generation technique using UML 2.0 Activity Diagram, which is a behavioral type of UML diagram. Like other model-based techniques, this technique can be used in the earlier phases of the development process owing to the availability of the design models of the system. The Activity Diagram model is seamlessly converted into a Colored Petri Net. We proposed a technique that enables the automatic generation of test sequences according to a given coverage criteria from the execution of the Colored Petri Nets model. Two types of structural coverage criteria for AD based models, namely sequential and concurrent coverage are described. The proposed technique was applied to an example to demonstrate its feasibility and the generated test sequences were evaluated against selected coverage criteria. This technique can potentially be adapted to service oriented applications, workflows, and concurrent applications.