The citrate sol-gel process was used to produce Sr2FeO4 strontium ferrite powder. The method involves metallic nitrates, citric acid and distilled water as a solvent, followed by calcination. The Ruddlesden-Popper structure of the resulting compound was identified by XRD analysis. The different molecular structures and vibration bands were studied by FTIR. The morphology of the powder was analysed using SEM. Samples appear of good crystalline quality and with interesting nanostructure. We studied optical properties and determined the band gap energy to lie about 2.8 eV, Sr2FeO4 can thus absorb photons having a wavelength less than 444 nm, approximately, making this compound potentially interesting for applications.