All available transitions from microwave to visible region (0.2-12 105 cm-1) of the HD18O molecule were collected and tested using the RITZ computer code. Literature data were completed by transitions assigned to HD18O in long path Fourier transform absorption spectra of the H2O, HDO and D2O gas mixtures with natural abundance of oxygen-18. In addition about 40 unassigned lines between 4200 and 6600 cm-1 of our previous water study associated with the HD18O molecule have been found and assigned. The new long path absorption spectra of the HDO and D2O mixtures allow us to observe about 1000 transitions of HD18O in the 6125-10 720 cm-1 spectral region. These data have been critically analyzed and used to obtain the most complete and precise set of the experimental energy levels of this molecule. © 2009 Elsevier Ltd. All rights reserved.