In the present work we have used the best available solar spectral data together with our absolute neon ionization cell data to estimate the absolute solar soft X ray flux and its variation with solar activity in the 20- to 100- ¿ region. Since the neon chamber data cover the integral spectral region from 20 to 575 ¿ we have constructed a composite spectrum covering that region so that the fraction of solar flux in the 20- to 100-¿ region could be determined. Both sounding rocket and satellite observations obtained over the past two decades have been used in the present analysis. Most of these prior data were acquired during low and moderate solar activity levels in contrast with the neon ionization cell data which were obtained during moderate and maximum solar activity levels. Based on these combined data sets we have shown the dependence of the integrated solar soft X ray flux between 20 and 100 ¿ on the daily 10.7 cm radio flux observed at 1 AU and have obtained an estimate of the maximum flux that can be expected over the solar cycle. ¿ American Geophysical Union 1989