The infrared spectra of the antisymmetric stretching bands of dilute solutions of nitrite and nitrate ions in sodium bromide are proposed as pressure gauges for use with anvils and other apparatuses. Their frequencies, which are at 1279.0 and 1401.3 cm−1respectively at zero pressure, were measured up to 186 kbar relative to theR1fluorescence line of ruby. The pressure is related to the shift &Dgr;&ngr; of the frequency of the nitrite ion at 22 °C from the zero‐pressure value by the equationp/kbar=2.356(&Dgr;&ngr;/cm−1)−1.334(&Dgr;&ngr;/cm−1)exp(−&Dgr;&ngr;/92 cm−1), and to the shift &Dgr;&ngr; of the frequency of the nitrate ion by the equationp/kbar=1.775(&Dgr;&ngr;/cm−1)−0.7495(&Dgr;&ngr;/cm−1) ×exp(−&Dgr;&ngr;/78 cm−1). Both equations were fitted by least squares, assuming that the error is in the pressure only, and the standard deviation of the pressure is 1.1 and 1.4 kbar, respectively.