DNA compaction induced by dodecyltrimethlammonium bromide (DTAB) is studied using atomic force microscopy (AFM) and magnetic tweezers. The morphology of DNA-DTAB complex is dependent on the DTAB concentration and incubation time. With magnesium ions, the complexes show rod- and network-like structures after approximately 5 min of incubation time, more toroids and globules appeared resulting in the formation of scattered condensed particles. At high DTAB concentrations, the complexes show swollen globular structures independent of the incubation time. The compaction and unraveling of the DNA-DTAB complex are also analysed at the single-molecule level using magnetic tweezers. The extension-time curves show a staircase structure with typical sizes of similar to 40, 60, 80 and 112 nm, suggesting that the complexes are well organised and more compacted than those induced by multivalent ions. Finally, the high DTAB concentration stabilized the complex and increased the unraveling energy barrier.