The regeneration of diesel particulate filters (DPFs) is a subject that has attracted considerable interest. Although the ozone (O3) injection method is effective, it is unclear whether it can be used to achieve complete DPF regeneration. From the applicative and fundamental points of view, the uncertainty is about whether the diesel particulates, which include nanoparticles, can be completely oxidized by means of plasma. In this entry, the possibility of complete DPF regeneration by evaluating the difference between the inlet and outlet pressures of the DPF is investigated in a laboratory scale. The experimental results show that complete regeneration can be achieved using an O3 injection rate of 34.8 g/h for 2 hours, after 2 hours of particulate matter collection. Furthermore, a theoretical analysis for the DPF regeneration based on the proposed chemical reactions is presented. Regeneration results agree well with the theoretical ones. On the basis of the results of DPF regeneration in a laboratory scale, a pilot-scale experiment is performed to establish a method implementing nonthermal plasma-induced radicals for DPF regeneration of marine diesel engines. The pressure difference decreases only when plasma is turned on, and DPF regeneration is realized at 320°C. The amount of O3 required for regeneration is determined under various engine operating conditions, and the basic characteristics of regeneration are elucidated. The plasma energy required for emission control of the entire gas is approximately 5% of the generated power of the marine engine.