Unique fluorogenic and chemiluminescence substrates for alkaline phosphatase (ALP), 2-(N-phenylphthalimidyl)benzothiazolyl-5-phosphate and 2-(2′,3′-dihydro-1′,4′-dionephthalazyl)benzothiazolyl-5-phosphate, respectively, that contain a highly fluorescent benzothiazole moiety as the fluorophore were synthesized and their applicabilities to the assay of ALP were examined. The chemiluminogenic substrate exhibited a linear chemiluminescence response to the amount of ALP in the range 0–20 pmol.