Intricate　Fenton-like　catalysts　composed　of　mixed　transition　metal　oxides　(TMOs)　frequently　outperform　simple　TMOs　in　scavenging　organic　contaminants　in　wastewater.　Nonetheless,　their　activity　and/or　reusability　may　sharply　decline　when　abundant　heavy　metal　ions　in　wastewater　adsorb　on　the　catalytic　surface　and　passivate　it.　This　study　shows　that　mesoporous　Ca-Mn　mixed　oxides　prepared　from　a　facile　combination　of　Mn　and　an　alkaline　earth　metal　(i.e.,　Ca)　(denoted　as　CaMnx)　can　readily　overcome　this　problem.　CaMnx　without　any　additive　(e.g.,　H2O2)　was　able　to　degrade　organic　contaminants　(e.g.,　indigo　carmine　as　a　model　contaminant)　fast　within　10　seconds,　outperforming　many　other　reported　heterogeneous　Fenton　catalysts.　Besides　organics,　the　coexisting　heavy　metal　ions　(e.g.,　Cu2+　and　Pb2+　as　indicators)　were　also　rapidly　extracted.　The　outstanding　performance　was　attributed　to　the　synergy　of　Ca　and　Mn.　CaO　in　CaMnx　efficiently　extracted　metal　ions　via　an　ion　exchange　process,　and　MnOx　generated　abundant　H2O2　and　degraded　the　organics　through　an　uncommon　Fenton-like　reaction.　Therein,　Cu　species　extracted　by　CaO　catalyzed　the　decomposition　of　H2O2　into　HO　radicals,　speeding　up　the　degradation　reaction　of　the　organics　by　81　times.　Benefiting　from　the　gradual　exposure　of　fresh　Mn-sites　protected　by　unreacted　CaO,　CaMnx　without　regeneration　treatment　maintained　high　efficiency　in　scavenging　organics　and　heavy　metal　ions　in　cycling　tests.　CaMnx　also　showed　great　promise　in　treating　complex　water　samples　containing　various　heavy　metal　ions　(e.g.,　Pb2+,　Cu2+,　Cd2+,　Ag+,　Zn2+　and　Cr3+)　and　organic　pollutants.　The　findings　of　this　work　enrich　the　rational　design　of　related　functional　nanomaterials.