Today businesses and Social Media are more diverse than ever before. On the one hand, this diversity influences the development of society; on the other hand, it also entails changes in Communication Behaviour. Currently Weblogs, already described as dead web-matter, are experiencing a new renaissance. Through high-quality contributions, Corporate Blogs offer the opportunity to interact with different groups of addressees, to communicate up-to-date information and, moreover, to actively manage Customer Knowledge. Therefore, this master thesis asks the research question of how Corporate Blogs can be used to improve Customer Communication and what are the strengths, weaknesses, opportunities and risks of Corporate Blogs for a companys Customer Knowledge Management. In order to provide a general understanding, an insight into the subject matter of Web 2.0 is given. Subsequently, the possibilities of an interactive Knowledge Management in External Corporate Communication are clarified. In particular, the company's Customer Knowledge Management and Customer Communication will be discussed. Furthermore, the history of Corporate Blogging is described and the importance of the Social Media Instrument Corporate Blog is shown. The empirical part of this master thesis provides information on how companies can use blogs as an eCKM- Tool in External Corporate Communication. Based on a content analysis, communication-relevant possibilities of corporate blogs are presented. By using a SWOT-Analysis, the potential of Corporate Blogs is shown.