The study aims to understand the strategic importance of effective complaint management in business-to-business (B2B) relations. The study explores the traits and actions that influence purchasing firms during the supplier complaint management process. The second aim is to reveal whether there are different expectations in the complaint management process between B2B and business-to-consumer (B2C) relationships. Semi-structured interview is used in the analysis. Questions are asked to 19 participants to investigate their perspectives on complaint management systems in B2B and B2C contexts and whether there are different influences between the two contexts. Participants are chosen from different hierarchical levels of different-sized firms. This helps see if there are different expectations in different hierarchical levels. Findings reveal that consumers highly value effective complaint management systems, which affect their purchasing decisions. It is considered that complaints in the B2B context are more important than those in the B2C context.