Recent reports have described deuterium exchange reactions on polyolefins; such isotopic labeling enables powerful analytical techniques, but exchange on isotactic polypropylene was previously unsuccessful. Here, we report successful exchange reactions on isotactic and syndiotactic polypropylenes, revealing the key role that the polymer stereochemistry and reaction solvent play in the mechanism of adsorption and exchange. Alteration of the polymer stereochemistry accompanies exchange in some cases, though molecular weight is preserved in all reactions.