Chemiluminescence　was　observed　when　some　acidic　triphenylmethane　dyes　were　oxidized　with　hydrogen　peroxide　in　alkaline　solution.　Trace　amounts　of　Co(II)　catalysed　this　chemiluminescent　reaction　strongly,　especially　in　the　presence　of　the　cationic　surfactant　cetyltrimethylammonium　bromide.　The　chemiluminescence　spectra　of　some　compounds　and　the　absorption　spectra　of　some　products　of　the　chemiluminescent　reactions　were　investigated,　and　some　acidic　triphenylmethane　dyes　were　studied　by　the　Hückel　molecular　orbital　method.　On　the　basis　of　these　investigations,　a　possible　mechanism　for　this　chemiluminescent　reaction,　and　an　initial　explanation　for　the　relationship　between　the　structure　of　the　reagents　and　their　chemiluminescent　behaviour　were　proposed.　The　optimum　conditions　for　use　of　some　of　the　chemiluminescent　reaction　systems　were　selected　by　means　of　the　modified　simplex　method,　and　a　chemiluminescent　analytical　method　for　determination　of　ultratrace　amounts　of　cobalt　was　established,　with　a　detection　limit　of　5　pg/ml.　It　was　used　for　analysis　of　natural　water　samples,　and　good　results　were　obtained.　©　1988.