We studied the electronic structure of metastable Fe1-xCox alloys using X-ray photoelectron spectroscopy (XPS). The samples studied here were metastable Fe1-xCox thin films produced by (potentiostatic) electrodeposition. The valence band XPS spectra depend mostly on the crystal structure and the filling factor of the 3d band. These spectra are relatively insensitive to the relative concentration because the atomic potentials of Fe and Co are similar. The spectrum of the Fe20Co80 (body-centered cubic, bcc) alloy resembles a rigid-bandshift (RBS) of the spectrum of pure Fe (bcc). The spectra of pure Co (hexagonal close-packed, hcp) and the Fe10Co90 (face-centered cubic, fcc) alloy are also similar because these structures are closely related. Theoretical simulations based on the RBS model reproduce the main features observed in the experimental spectra. The experimental and theoretical results are in good agreement with previous linear muffin tin orbital-coherent potential approximation (LMTO-CPA) band calculations. This confirms that disorder effects, which are not considered explicitly in the RBS model, are not dominant in this system. (C) 2003 The Electrochemical Society.