This paper reports on the optical and electrical characterisation of Ta 2O 5 thin films deposited by electron beam evaporation from sintered ultrapure Ta 2O 5 powders as source. The substrates were fused silica and aluminium-coated Si wafers to allow optical and electrical analysis respectively. Two samples were grown at temperatures of 100 °C and 200 °C, at partial O 2 pressure of 5 × 10 −2 Pa and thickness of 0.65 μm and 1.25 μm, respectively. The analysis pointed out that the two samples showed high electrical resistivity and that no noticeable optical absorption in the visible spectrum was found. Complex dielectric functions, electrical field breakdown, optical transmittance and direct gap measurements were made to provide minimum quality standards to produce Ta 2O 5 films for electro-optical devices.