Polymer-supported acetals 1 and 2 have been prepared by reaction of hydroxy acetals of decanal 6 + 7 and 8 with a Merrifield resin, whereas the glycol 3 and the related 2-nonyl dioxolane 4 have been prepared from a polystyrene resin. The polymer-supported acetals 1, 2 and 4 release decanal in a stream of moist air when an acid catalyst is previously imbedded in the polymer. Similarly, 4-phenyl-2-nonyldioxolane 5 affords decanal when imbedded in a polystyrene resin along with an acid catalyst.