In recent years, the problems related to modeling and improving business processes has been of growing interest. The scientific problem addressed in this paper consists in modeling and improving Business Process (BP) models quality. This problem is of growing interest as companies are realizing the undeniable impact of a better understanding of Business Processes (BP) on the effectiveness, consistency and transparency of their business operations. The research aims at proposing methods and tools for BP model quality measurement and improvement. The authors propose a semantic approach of quality exploiting domain knowledge.