This paper presents an appropriate categorization of business processes in order to study the different aspects of knowledge management for each kind of business processes. In this categorization, business processes are classified into the four categories including work-flow oriented, decision oriented, information oriented and motivation oriented. Then, the special attributes and knowledge management barriers for each kind of business processes are discussed. Findings from the literature led to some hypotheses about the most important knowledge management barriers in the four different kinds of business processes. Tentative theory has improved through two case studies for a work-flow oriented business process and a decision oriented business process. Research findings help managers to have process perspective in implementing KM initiatives and remove the most important barriers of KM regarding the type of the considered business processes. Improving the hypotheses related to the information oriented and collaborate oriented business processes through case study in their instance processes and also testing the introduced hypotheses are good start points for further research in the future.