Herein is described a new species of hylid frog from low elevations in the Atlantic Rain Forest, along the southern coast of the State of Rio de Janeiro and northern coast of the State of São Paulo, Brazil. The larvae and the site of reproduction are also described. It is a medium-sized species of the genus Hyla and is included in the Hyla albofrenata group by virtue of having lime green color of the body, orange-red iris without bicolored ring, voices sounding like drops of water falling into an empty bottle, and inhabiting mountain stream forests. The new species is very similar to Hyla albofrenata, from which it can be separated by its smaller size, larger calcar, length of the femur and tibia larger than the snout–vent length (SVL), by the clear coloration of the iris, morphology and coloration of the tadpole, and geographic distribution. The new species is also similar to Hyla ehrhardti from which it can be separated by having longer legs, presence of the calcar developed, presence of a supra-anal crest, color of the iris and northern distribution. It can be easily distinguished from Hyla arildae, Hyla musica, and Hyla weygoldti by possessing a curved and short supratympanic fold, by having a well-developed calcar and by its smaller SVL.