A new caddisfly species, Electroadicella unipetra sp. nov., is described from Rovno amber (upper Eocene, 36 million years old). This species belongs to the family Leptoceridae, which includes 2000 species globally, with 23 reported from amber. Electroadicella is a genus known only from Eocene European amber, with six fossil species previously described. The new species is the third from Rovno amber and represents a significant addition to the genus, which is the most specious Eocene leptocerid genus. The species is characterized by its elongated medial branches of inferior appendages, reduced lateral branches, and a broad, short X segment. The male genitalia are described in detail, showing distinct features such as long, narrow, pointed and recurved processes above the inferior appendages. The species is named in honor of Saint Petersburg State University's 300th anniversary. The new species is part of a broader study of caddisflies from Rovno amber, which now includes 38 named species, with 10 also known from Baltic amber. The study highlights the importance of Rovno amber in understanding the diversity of caddisflies in the Eocene, with many species being endemic to the region. The paper also discusses the ecological and climatic factors influencing the distribution of these species, including the warmer climate of Rovno compared to Baltic amber. The study contributes to the understanding of the paleontological and taxonomic diversity of caddisflies in European amber deposits.A new caddisfly species, Electroadicella unipetra sp. nov., is described from Rovno amber (upper Eocene, 36 million years old). This species belongs to the family Leptoceridae, which includes 2000 species globally, with 23 reported from amber. Electroadicella is a genus known only from Eocene European amber, with six fossil species previously described. The new species is the third from Rovno amber and represents a significant addition to the genus, which is the most specious Eocene leptocerid genus. The species is characterized by its elongated medial branches of inferior appendages, reduced lateral branches, and a broad, short X segment. The male genitalia are described in detail, showing distinct features such as long, narrow, pointed and recurved processes above the inferior appendages. The species is named in honor of Saint Petersburg State University's 300th anniversary. The new species is part of a broader study of caddisflies from Rovno amber, which now includes 38 named species, with 10 also known from Baltic amber. The study highlights the importance of Rovno amber in understanding the diversity of caddisflies in the Eocene, with many species being endemic to the region. The paper also discusses the ecological and climatic factors influencing the distribution of these species, including the warmer climate of Rovno compared to Baltic amber. The study contributes to the understanding of the paleontological and taxonomic diversity of caddisflies in European amber deposits.