Hydrosodalites and hydroxosodalites were analysed by means of O-17, Si-29 and H-1 MAS NMR in the fields of 17.6 and 11.7 T. The samples covered a range in Si-O-Al bond angle of about 23degrees. Dependencies between the isotropic O-17 chemical shift 50 10) and the T-O-T bond angle a for the oxygen sites in socialites, A and LSX zeolites with Si/Al = 1 were investigated and found to be linear in some special cases. The adsorption of water and/or cation exchange with larger cations increases the 110 chemical shift. (C) 2003 Elsevier Science B.V. All rights reserved.