A transmission grating extreme ultraviolet (EUV) spectrometer, nominally identical to the Charge, Element, and Isotope Analysis System/Solar EUV Monitor (CELIAS/SEM) instrument on the Solar and Heliospheric Observatory (SOHO), has obtained accurate measurements of the integrated absolute solar extreme ultraviolet irradiance in an 8 nm band pass centered at 30.4 nm. The spectrometer also measured the EUV/soft X-ray flux, but those data will be reported in a later paper. The instrument was launched on two sounding rocket flights from White Sands Missile Range, New Mexico, on June 26, 1996, and again on August 11, 1997, to provide a SOHO underflight calibration database in the EUV. The full disk solar 30.4¿40 nm fluxes measured by it on the above 2 days were 1.21¿1010 and 1.42¿1010 photons cm-2 s-1 at 1 AU, respectively. These measurements have an absolute 1&sgr; uncertainty of 8.1%. ¿ 1999 American Geophysical Union