We present the design, implementation, and on-ground performance measurements of the Ionospheric Connection Explorer EUV spectrometer, ICON EUV , a wide field ( 17 ∘ × 12 ∘ ) extreme ultraviolet (EUV) imaging spectrograph designed to observe the lower ionosphere at tangent altitudes between 100 and 500 km. The primary targets of the spectrometer, which has a spectral range of 54–88 nm, are the O ii emission lines at 61.6 nm and 83.4 nm. Its design, using a single optical element, permits a 0 . ∘ 26 imaging resolution perpendicular to the spectral dispersion direction with a large ( 12 ∘ ) acceptance parallel to the dispersion direction while providing a slit-width dominated spectral resolution of R ∼ 25 at 58.4 nm. Pre-flight calibration shows that the instrument has met all of the science performance requirements.