The present article is the third part in a series of studies on the i-prefix found in several verb forms in the earliest Old Egyptian. It is argued that, rather like in the sDm-f formation, in participles this element stood for an initial glottal stop used primarily with two-radical roots. By extending the stem, its introduction allowed the creation from these roots of participles whose syllabic structures conformed to the general Semitic participial template and were identical to those formed of roots with three radicals. It is further argued that the prefixed forms were later lost probably through a combination of phonological erosion and analogical pressure within the participial system. A brief discussion is also devoted to the very unclear instances of the i-prefix in participles from root-classes other than 2rad.