We used FLAMES@VLT spectra of 45 stars in the globular cluster NGC 6535 to measure radial velocity and infer cluster membership, to derive atmospheric parameters and abundances (in particular of the light elements O and Na). We find a O-Na anticorrelation, as normal for a GC. We also compile a list of clusters known to host (or not) multiple populations on the basis of their chemistry. (1 data file).