Electrochemistry　of　hot　electrons　in　fully　aqueous　solutions　at　tetrahedral　amorphous　carbon　thin　film　electrodes　is　discussed.　The　generation　of　these　highly　reducing　chemical　species　was　confirmed　by　normal　pulse　voltammetry　and　several　electrochemiluminescent　systems.　Electron　transfer　into　pre-existing　solvent　cavities　was　observed　at　approximately　−2.65　V　vs.　Ag/AgCl　(sat.).　Electrogenerated　hot　electrons　were　utilized　as　chemiluminescent　mediators　in　heterogeneous　sandwich　immunoassay　of　Serum　Amyloid　A.　The　calibration　curve　was　linear　over　four　orders　of　magnitude　and　the　detection　limit　was　85　ng　L−1　that　demonstrates　the　efficiency　of　hot　electron　generation　at　this　electrode　material.　©　2022　Wiley-VCH　GmbH.