A series of novel 2-carboxylic acids of the title ring systems has been synthesized from the corresponding 3-acetyl-4H-[1]benzopyran-4-one and benzothiopyran-4-one. These acids were examined for their ability to inhibit the rat passive cutaneous anaphylaxis; the pyridinone carboxylic acids 6 displayed a higher degree of iv and ip anaphylactic activities than their pyranone analogues 5. The potassium salt 5a (R6 = K) was the only compound that exhibited a moderate oral activity.