Technical Abstract: Free zone capillary electrophoresis conditions have been improved to allow rapid separations of grain proteins from several cereals (wheat, oats, rice, barley, and rye) with high resolution and reproducibility. Gliadins were separated in < 8 min, oat and rice prolamins in < 2 min, and barley prolamins in < 4min. Glutenins were separated in ~ 3 min, oat and rice glutelins in <3 min, and rye glutelins in <4 min. This method utilized the isoelectric compound, iminodiacetic acid (IDA) in conjunction with acetonitrile and hydroxypropylmethyl-cellulose. Cultivars of all cereals tested could be differentiated in 3 min, including wheat using either prolamin or glutelin protein patterns. Resolution was similar, or higher, than that of separations in other acidic buffers. Migration time repeatability was excellent with run-to-run variability <1% relative standard deviation (RSD), day-to-day <1.4% RSD, and capillary-to-capillary <3.3% RSD. Larger inner diameter capillaries (50 um) could be used with this buffer thereby increasing sensitivity and reducing rinse times. This method allows unattended, high throughput (~180 to 400 samples/24 hours) separations of cereal proteins without generating organic solvent waste and allows automated data analysis and storage.