Absorption spectra of HDO/D2O mixtures recorded in the 5600-8800cm-1 region with a total pressure of water from 13 up to 18hPa and an absorption path length of 600m have been analyzed in order to obtain new spectroscopic data for HD18O and D2 18O. In spite of the low natural 18O concentration (about 2×10-3 with respect to the 16O one), about 1100 transitions belonging to HD18O and more than 280 transitions belonging to D2 18O have been assigned. Most of the D2 18O transitions belong to the v1+v2+v3 and 2v1+v3 bands. Sets of energy levels for seven vibrational states of D2 18O and four states of HD18O are reported for the first time. The comparison of the experimental data with the calculated values based on Partridge-Schwenke global variational calculations is discussed. © 2010 Elsevier Ltd.