Okadaic Acid (OA), a small seafood-borne toxin secreted by Dinophysis and Prorocentrum dinoflagellates, is generally distributed in various species of shellfish and has caused diarrhetic shellfish poisoning (DSP). In view of OA toxin threat to humans and animals, it is essential to develop a rapid, accurate and sensitive method for the detection and quantification of OA in real samples. In this study, a monoclonal antibody named 10E8 was screened by cells fusion of Sp2/0 with spleen cells isolated from immunized mouse, and the isotype of McAb 10E8 was belonged to IgGl. The resulted McAb 10E8 displayed higher specificity to OA antigen, with the highest affinity of 2.66 x 10(9) L/moL until now. Indirect competitive ELISA (ic-ELISA) indicated that the linear range to detect OA was 20-750 ng/mL. The limit of detection (LOD) was 12 pg/mL, and the recovery average was (84.04 +/- 5.08)%. The LOD of colloidal gold immunoassay by naked eye and strip reader was 1 ng/mL and 100 pg/mL, respectively, with an average recovery of (88.0275 +/- 4.4225)%. Therefore, the developed ELISA and colloidal gold immunoassay based on this McAb can be used for OA detection in real samples. (C) 2017 Elsevier B.V. All rights reserved.