  At low redshifts, measurements of the total baryon content in stars, atomic
and molecular hydrogen, and cluster gas fall a factor of two to four below the
baryon density derived from observed light-element ratios and nucleosynthesis
arguments. A possible hiding place for a significant fraction of the missing
baryons is in the warm/hot gas at temperatures T = 10^{5}-10^{7}K. We present
predictions of the contribution to the soft X-ray background from warm/hot gas
emission calculated using new hydrodynamical simulations and discuss the
possibility of detecting the spectral signature of this gas using the Chandra
X-ray Observatory.
