Almost 20 years after the bursting of the dot-com bubble, we are again experiencing a boom in B2B electronic marketplaces. These marketplaces usually connect buyers and suppliers in the digital sphere; however, the implementation of a marketplace comes with numerous challenges in the B2B sector. Marketplace operators often reach their limits, especially at the operational level. Based on expert interviews with five electronic marketplaces from the chemical industry and from other data sources, we have collected these challenges and classified them into four categories: (1) Technical Level, (2) Individual & Cultural Level, (3) Corporate Level, and (4) Industry Level. The categories presented in this case study extend an existing research model that deals with the adoption of B2B electronic marketplaces. This theory development provides a deeper understanding of electronic marketplaces, which is important for both researchers and practitioners. The mastering of these challenges has a major influence on the adoption of the respective marketplace as well as on its success or failure.