The model neutral exosphere of O¨pik and Singer for a nonrotating planet is generalized by permitting the corresponding barosphere to rotate uniformly at an angular velocity which may or may not be equal to that of the planet. For this case the velocity‐distribution function, satisfying the collisionless Boltzmann equation, is constructed. Then, the density is determined from the distribution and compared with the corresponding result for a nonrotating planet obtained by O¨pik and Singer. In addition, the radial and azimuthal fluxes are derived. Based on the result for the azimuthal flux, the point at which exospheric corotation can be said to have broken down is indicated for several conditions. It is shown that in all cases, for a given radius, the density at the equator exceeds the density at the pole. For example, a model terrestrial neutral exosphere of hydrogen, helium, and oxygen has density ratios between the pole and the equator of 0.984, 0.869, and 0.530, respectively, atr = 2R.