The　kinetics　of　keto-enol　tautomerism　of　p-hydroxyphenylpyruvic　acid　(pHPP)　as　a　model　of　α-carbonyl　compounds　in　aqueous　solution　at　room　temperature　(25　°C)　was　first　investigated　by　capillary　electrophoresis　with　UV　detection　at　200　nm.　The　two　tautomers　could　be　separated　and　detected　within　3　min.　Since　the　ketonization　of　enolic　pHPP　varied　with　the　buffer　composition　and　buffer　pH,　the　kinetics　of　pHPP　was　studied　under　different　conditions,　and　relevant　distributing　fractions　of　enolic　pHPP,　ketonization　rate　constants　and　half-life　were　determined.　In　addition,　β-CD　played　an　important　part　in　the　separation　of　the　two　tautomers,　thus,　the　interaction　between　pHPP　and　β-CD　was　also　investigated　by　electrochemical　techniques.　©　2007　Elsevier　B.V.　All　rights　reserved.