Functional MRI is a blood-based marker of neural activity. The transfer function relating the two is the hemodynamic response function (HRF), which varies across both brain regions and individuals. It is traditionally considered a confound in fMRI analysis; however, the underlying biophysics suggests that HRF might in part reflect local neurochemical substrates, specifically glutamate, GABA and serotonin. Here, we found evidence that HRF shape is associated with, and predictive of, 1H MRS glutamate in thalamus. These results open the possibility of approximating neurochemical concentrations using resting-state fMRI. Future studies could validate this in an independent and larger sample.