Giuseppe Raddi collected in the state of Rio de Janeiro, Brazil, from November 1817 to June 1818. He published 12 new names in the family Piperaceae in an article that appeared in 1828. Raddi's article has not been cited in specialized literature and these names were never properly studied. In the present study, these names are typified, and their identity is clarified. Five new combinations are here presented, namely Peperomia callitrichoides, P. catesbaeifolia, P. cylindrica, P. gracillima, and P. plantaginifolia. The new name Piper raddianum is published, honoring him and his botanical accomplishments. In addition, the names Piper scutatum, Piper scolopendrifolium, Piper truncatum, Piper fluminense, Steffensia ampla (≡ Piper amplum), Piper variabile, Piper catesbaeafolium, Piper cylindricum, Piper pumilum, Peperomia martiana, and Piper gracillimum are here lectotypified.