The foundation of a process model lies in its control flow specifications. Using a generic process modeling language for workflows, we show how a control flow specification may contain certain structural conflicts that could compromise its correct execution. In general, identification of such conflicts is a computationally complex problem and requires development of effective algorithms specific for target system language. We present a visual verification approach and algorithm that employs a set of graph reduction rules to identify structural conflicts in process models for a generic workflow modeling language. We also provide insights into the correctness and complexity of the reduction process. The main contribution of the paper is a new technique for satisfying well-defined correctness criteria in process models.