In order to assess the contribution of carbonyl sulfide to stratospheric sulfate aerosol (SSA), we examined the stratospheric OC34S and OC32S concentration profiles in the infrared limb-transmittance spectra acquired by the JPL MkIV instrument. We found that OC34S is preferentially depleted by solar photolysis. The derived 34S enrichment factor: ϵ = +73.8 ¿ 8.6?, in conjunction with literature values of δ34S ~ +11? for tropospheric OCS, and a ~ 10% net processing of the OCS transported upwardly into the stratosphere, suggests that aerosol sulfate proceeding from OCS should be highly enriched in δ34S ~ 80?, comparing our prediction with previous reports of δ34S ~ +2.6? for background SSA, we infer either that OCS is a minor contributor to SSA or that current views about its 34S-abundance and atmospheric circulation are seriously flawed.