Preferential solvation of Na+ by N,N-dimethylformamide (DMF) in a DMF-water binary mixture is observed at the cluster level through mass spectrometry. Since DMF is highly electron donating, the Na+-DMF interaction is more favorable than the DMF-H2O interaction. The observed clusters in a DMF-water mixture with and without NaCl, show that once a DMF molecule interacts with Na+, the DMF molecule hardly forms a hydrogen bond with a water molecule or cluster.