Monitoring is considered as one of the key functions in workflow management systems (WfMS). Monitoring provides users with the real-time information of the business processes which are being executed in a WfMS. Information collected for monitoring is usually used by the analysts for business process improvement as well as for decision making. In this paper we propose an object-based approach to workflow monitoring. In this approach, all basic elements in WfMS are divided into “Data Objects”. User can monitor the required information by combining simple data objects to form new complex objects. Specifically, fundamental data objects can be dynamically extended for monitoring complex business data. A SQL like query language is also developed to retrieve data objects for the monitoring functions. Based on the proposed approach, user can monitor the workflow status and other key performance indicators by defining different customizable views with various data objects.