Electrospinning of the globular protein, bovine serum albumin (BSA), was optimized to obtain proteinous fibers suitable as biosensors. It was shown that the as-spun protein preserves its native form, whereas solubility of the cross-linked in the ambient conditions BSA nanofibers evidently decreases. Insoluble BSA fibers cart be easily modified to be used as two-dimensional biosensors. Here, we show the micro pH sensor obtained from the BSA fiber stained with a fluorescein derivative (FITC).