The hydration of clays and shale in drilling operations may be inhibited by employing an aqueous based drilling fluid comprising a shale hydration inhibition agent having the formula: (I), R is an alkyl group having 1 to 6 carbons; R1 may be the same or different than R and is an alkyl group having 1 to 10 carbons or a hydroxy alkyl group comprising n number of carbons wherein n is an integer from 1 to 10 and n−1 hydroxyl groups; R2 is an alkyl group having 1 to 6 carbons; R3 may be the same or different than R2 and is an alkyl group having 1 to 10 carbons or a hydroxy alkyl group comprising n number of carbons wherein n is an integer from 1 to 10 and n−1 hydroxyl groups, with the proviso that R3 is not the same as R1; and X is an anion. The shale hydration inhibition agent should be present in the aqueous based drilling fluid in sufficient concentration to reduce the reactivity, such as swelling, of clays and shale when exposed to water-based drilling fluids.