Single　atom　catalysts　(SACs)　can　achieve　a　maximum　atom　utilization　efficiency　of　100%,　which　provides　significantly　increased　active　sites　compared　with　traditional　catalysts　during　catalytic　reactions.　Synchrotron　radiation　technology　is　an　important　characterization　method　for　identifying　single-atom　catalysts.　Several　types　of　internal　information,　such　as　the　coordination　number,　bond　length　and　electronic　structure　of　metals,　can　all　be　analyzed.　This　review　will　focus　on　the　introduction　of　synchrotron　radiation　techniques　and　their　applications　in　SACs.　First,　the　fundamentals　of　synchrotron　radiation　and　the　corresponding　techniques　applied　in　characterization　of　SACs　will　be　briefly　introduced,　such　as　X-ray　absorption　near　edge　spectroscopy　and　extended　X-ray　absorption　fine　structure　spectroscopy　and　in　situ　techniques.　The　detailed　information　obtained　from　synchrotron　radiation　X-ray　characterization　is　described　through　four　routes:　1)　the　local　environment　of　a　specific　atom;　2)　the　oxidation　state　of　SACs;　3)　electronic　structures　at　different　orbitals;　and　4)　the　in　situ　structure　modification　during　catalytic　reaction.　In　addition,　a　systematic　summary　of　synchrotron　radiation　X-ray　characterization　on　different　types　of　SACs　(noble　metals　and　transition　metals)　will　be　discussed.　©　2022　Wiley-VCH　GmbH.