In recent years the problems related to modeling and improving business processes have been of growing interest. Indeed, companies are realizing the undeniable impact of a better understanding and management of business processes (BP) on the effectiveness, consistency, and transparency of their business operations. BP modeling aims at a better understanding of processes, allowing deciders to achieve strategic goals of the company. However, inexperienced systems analysts often lack domain knowledge leading and this affects the quality of models they produce. Our approach targets the problem related to business process modeling quality by exploiting Petrinets notation and detecting syntactic defects. We propose to support this modeling effort with an approach that uses OCL rules to prevent these defects. The main contribution of this master thesis is threefold: 1. Exploiting the different modeling notations that exists in the literature. 2. Detect syntactic and soundness defects. 3. Define OCL rules to improve these business process models. We conducted a survey to validate the selection of the quality constraints through testing the OCL rules on several models provided by provided by BPM Academic initiative (« BPM Academic Initiative | Signavio » 2013).