A library of coumarin derived sulfonyl esters (1-38) was synthesized by reacting various hydroxy coumarins with different alkyl and aryl sulfonyl chlorides. All compounds were evaluated for their potential to inhibit alkaline phosphatases (hTNAP and hIAP). Most of the compounds were found to be inhibitors of APs. Compound 20 was found to be the most active hIAP inhibitor (IC50 = 1.11 ± 0.15 μM), whereas, compound 13 was found to be the most active hTNAP inhibitor (IC50 = 0.58 ± 0.17 μM). Detailed structure activity relationship studies (SAR), and molecular docking studies were carried out to identify structural elements necessary for AP inhibition, in addition to rationalize most probable binding site interaction of the inhibitors with the AP enzymes.