Prostacyclin or prostaglandin I2 (PGI2), a metabolite of arachidonic cyclooxygenase pathway, has been demonstrated as an effector of adipocyte differentiation. However, due to its instability in biological fluid, it is difficult to evaluate the role of PGI2 in regulating adipocyte differentiation in different stages in culture. Therefore, this study aimed to establish a simple and rapid method for the production of monoclonal antibody against 6-Keto PGF1α, a stable PGI2 metabolite, and its quantification to determine the role of PGI2 in culture medium. Eight-week-old female BALB/c mice were immunized with the hapten of 6-Keto PGF1α and BSA for several weeks until a higher antibody titer (absorbance value > 0.9 at 1000-times dilution) against 6-Keto PGF1α was found. Then, fusion of antibody-producing spleen lymphocytes with SP-2 myeloma cells and thymocytes was performed and cultured in HAT-medium supplemented with hypoxanthine, aminopterin, and thymine. Specific antibody-producing cells (M2-A4-B8-D10) against 6-Keto PGF1α were identified and separated. A standard ELISA calibration curve was developed with 100% reactivity for 6-Keto-PGF 1 α ranging from 0.26 pg to 6.44 ng corresponding to 90% and 10% of the maximum binding capacity for the immobilized antigen respectively. This method can easily be applied to monitor PGI2 regulation in different stages of cultured adipocytes to reveal the regulatory roles of PGI2 in maintaining homeostasis and adipocyte differentiation. •The monitoring of adipocyte differentiation effector PGI2 in culture was difficult due to its instability.•A new ELISA method has been developed to quantify 6-Keto PGF1α, a stable metabolite of PGI2, to monitor the role of PGI2 in adipocyte differentiation.•A new hybridoma cell line producing monoclonal antibody against 6-Keto PGF1α has been generated.