The immobilization of DNA on different solid supports has become an important issue in different fields ranging from medicine to analytical chemistry and, more recently, molecular electronics. Among the different immobilization procedures, adsorption is the simplest and the easiest to automate, avoiding the use of procedures based on previous activation/modification of the substrate and subsequent immobilization, which are tedious, expensive and time-consuming. Carbon-based materials are widely used for this task due to their electrochemical, physical and mechanical properties, their commercial availability, and their compatibility with modern microchip fabrication technology. Moreover, carbonaceous materials are widely used as transducers for electrochemical sensors. The knowledge of the adsorbed DNA morphology on carbon surfaces can be used to develop stable and functional DNA layers for their use in DNA analytical devices with improved properties. Presented here is a concise description of surface immobilization of DNA, oligonucleotides, and DNA derivatives by adsorption onto carbonaceous materials, and the properties of the DNA layer adsorbed on carbonaceous solid phase.