Based on their unique properties various iron magnetic nanoparticles have proved to be excellent nanomaterials for applications in separation and concentration process. Immobilization of deoxyribonucleic acid (DNA) molecules on the magnetic beads are acutely important and have potential uses in many techniques such as DNA extraction, concentration, biosensors, microarrays and next generation sequencing. In this study the adsorption of single stranded DNA (ssDNA) via poly-l-lysine coated iron oxide magnetic beads was performed under varying conditions of poly-l-lysine amount, initial DNA concentration, ionic strength, bonding type and length of DNA. The adsorption process was examined via Langmuir and Freundlich isotherm models. The ionic interaction between negatively charged DNA and positively charged surface of magnetic beads showed multilayer adsorption with Freundlich adsorption isotherm, covalent bonding between modified DNA and surface by crosslinking provided higher adsorption efficiency with Langmuir adsorption isotherm. Both adsorption methods provided magnetic beads with favorable adsorption of ssDNA.