The proposal aims to investigate the formation of magnetic stripes in La2-xSrxCoO4. Recent measurements have revealed an hourglass magnetic spectrum at x=1/3. The question we address here is, how does this spectrum emerge from the commensurate antiferromagnetic phase at x=0? We will perform measurements of the magnetic excitation spectrum on crystals with x = 0.25 and x = 0.30. Data on the complete excitation spectrum will provide information on the nature of the magnetic correlations present, for example whether there is a phase separation into regions of disordered stripes and commensurate short-range order.