In　this　study,　we　compared　dissolved　organic　carbon　(DOC)　and　UV254　removal　efficiencies　of　the　hybrid　ozonation-coagulation　(HOC)　and　pre-ozonation-coagulation　(POC)　processes　for　humic　acid　(HA)　at　pH　5　with　AlCl3•6H2O　as　the　coagulant.　The　DOC　and　UV254　removal　efficiencies　of　the　HOC　process　were　higher　than　those　of　the　POC　process　at　ozone　dosages　less　than　2.0　mg　O3　(mg　DOC)−1.　The　ozone　dosage　was　optimized　at　0.3　and　0.1　mg　O3　(mg　DOC)−1　for　the　HOC　and　POC　processes,　respectively,　implying　a　more　rigorous　ozone　dosage　for　the　POC　process.　During　the　POC　process,　pre-ozonation　was　observed　to　increase　the　binding　sites　of　HA　(e.g.,　hydroxyl　and　carboxyl　groups),　improving　the　complexation　of　dissolved　organic　matter.　For　the　HOC　process,　in　addition　to　its　role　in　the　oxidation　of　organic　matter,　ozone　also　reacted　with　coagulants.　The　reaction　between　ozone　and　coagulants　can　facilitate　the　formation　of　Al13.　Moreover,　the　oxidation　of　•OH　and　ozone　can　increase　the　charge　density　of　the　HA　binding　sites,　homogenizing　the　binding　sites　of　HA　and　enhancing　the　complexation　with　Al13.　©　2021