This book constitutes the refereed proceedings of the 16th Conference on Computer Networks, CN 2009, held in Wisla, Poland, in June 2009. The 40 revised full papers presented were carefully reviewed and selected for inclusion in the book. The papers are organized in the following groups: new technologies applied in computer networks, particularly those related to nano, molecular and quantum technology; new standard technologies related to computer network structure; the fundamentals of computer networks, their architecture and programming; articles concerning the Internet in its broad meaning; papers related to data and analysis of industrial computer networks; and a group of articles describing general applications of computer networks, including issues related to the quality of data exchange.