Pelophylax demarchii is a species of frog in the family Ranidae. It is only known from its unspecific type locality, Eritrea. Its taxonomic status is unclear. Common name Eritrea pond frog has been coined for it.
The specific name demarchii honours, an Italian naturalist, hydrobiologist, industrialist, and philanthropist.
Pelophylax demarchii was described by Italian herpetologist based on two syntypes, of which one is lost. It is uncertain whether it is a valid species; it most closely resembles Pelophylax ridibundus and might be its synonym.
Ecological requirements, distribution, and current population status of this species are unknown. Consequently, it is listed as "data deficient" in the IUCN Red List of Threatened Species.