Epitaxial electrodeposition of Cu2O on Ag substrates in sulfate baths

•Cu2O were deposited on Ag from electrolytes containing 1.3 M lactic acid.•Epilayers were obtained at conditions of pH 12/25 °C, pH 9/60 °C, and pH 12/60 °C.•As many as five orientation relationships between Cu2O and Ag are identified.•The density of threading dislocations in epilayers was as low as 4x109 cm−2.•The epilayers exhibited low electrical resistivity values of 1–3 × 103 Ω·cm.