This diploma work focuses on freely available and professional electronic information resources for environmental issues. These resources are only accessible from computer networks (such as the Internet or other digital data distribution networks). The thesis is divided into three parts. The first part defines typical users of such resources in connection with their user needs. In the other two parts freely available and professional electronic information resources for environmental issues are classified and reviewed while several resources are completed with both qualitative and quantitative analyses. This work also contains analyses of resources availability and it is provided with charts and graphs for better understanding of the topic.