Cleavage　of　aryl　ether　(Caryl-O)　bonds　is　crucial　for　the　conversion　and　value-added　utilization　of　lignin　and　its　derivatives,　but　remains　extremely　challenging　under　mild　conditions　due　to　strong　Caryl-O　linkages.　In　this　study,　the　Caryl-O　bond　breaking　is　achieved　through　electrocatalytic　oxidation　of　four　phenolic　lignin　model　compounds　with　typical　Caryl-O　bonds,i.e.,　4-ethoxyphenol　(EP),　4-phenoxyphenol　(PP),p-benzyloxyphenol　(PBP),　and　2-(2-phenylethoxy)phenol　(2-PEP),　in　a　protic　ionic　liquid　[BSO3Hmim][OTf]-H2O　electrolyte,　and　the　electrocatalytic　oxidation　mechanism　is　also　fully　explored.　The　effects　of　H2O　on　the　viscosity　and　conductivity　of　the　[BSO3Hmim][OTf]　ionic　liquid　system,　as　well　as　the　solubility　and　diffusion　coefficients　of　O2and　the　four　lignin　substrates,　are　investigated　to　optimize　the　optimal　ratio　of　the　electrolyte　system　composed　of　[BSO3Hmim][OTf]　and　H2O.　Electrochemical　oxidation-reduction　behaviors　of　the　four　lignin　substrates　in　the　[BSO3Hmim][OTf]-H2O　system　and　the　effect　of　O2and　N2atmospheres　on　degradation　are　studied　in　detail　by　using　cyclic　voltammetry　(CV)　curves.　Finally,　by　combining　the　analysis　of　degradation　products　with　isotope　labeling　experiments,　the　C-O　bond　cleavage　mechanism　is　obtained,　which　mainly　involves　direct　and　indirect　oxidation.　Specifically,　under　a　N2atmosphere,　the　substrates　are　oxidized　directly　on　the　RuO2-IrO2/Ti　mesh　electrode　through　Caryl-O　bond　splitting　to　form　quinone　and　carbonium　ions,　while　under　an　O2atmosphere,　apart　from　the　direct　oxidation　on　the　electrode,　indirect　oxidation　of　the　lignin　substrates　also　occurs　throughin　situgenerated　H2O2.　This　study　may　provide　some　insight　into　developing　effective　strategies　for　efficient　utilization　of　lignin　under　mild　conditions.　©　The　Royal　Society　of　Chemistry　2021.