In the year 200 1, two issues remain for extreme high vacuum (XHV) pressure measurements with hot-cathode ionization gauges: measurement limits caused by electron-stimulated desorption (ESD) and outgassing. The limit caused by ESD is significantly clarified and at least partially solved by means of a grid heating method in a residual gas analyzer. After system bakeout and at 10(-9) Pa, when the surface of a platinum alloy grid remains contaminated with F and Cl atoms and CO molecules, the mass spectrum is dominated by spurious peaks (which set the measurement limit for a total pressure gauge) caused by ESD species of F, Cl, and O, with a yield of 10(-11) (species/ electron, with neutral/ion congruent to0.3) and by CO molecule ESD, with a yield of 10(-11) (species/electron, with CO neutral/O ion congruent to18). In this condition, a spurious H peak caused by hydrogen ESD is still low. However, once the grid surface is thoroughly cleaned at over 900degreesC by ohmic heating or electron bombardment, the major ESD species observed for both neutrals and ions dramatically changes to mainly a spurious H peak with a yield of 10(-11) (species/electron, with neutral/ion congruent to2). When the operational grid temperature is then increased to 500 degreesC, the spurious H peak is decreased by over 3 orders of magnitude and the spectrum becomes mainly H-2 molecules, reflecting the true pressure of the system; i.e., the relative error for the pressure is reduced to 8% from 614%. The lower limit caused by outgassing in these instruments is due to the grid bulk content of hydrogen. Finding a lower-hydrogen solubility material for the grid may become the last work required for lower-limit XHV gauge development. In order to decrease the limits caused by ESD and outgassing in a hot-cathode gauge, employing ion energy filters and cold-cathode field emitters is unnecessary.