A series of poly (methacrylic acid-Co-maleic acid), P(MAA-MA), hydrogels have been prepared by free radical polymerization in aqueous medium using different amount of maleic acid (MA) (0-5 wt.%), initiated by potassium persulfate (KPS) in the presence of N,N'-methylenebisacrylamide (MBA) as a crosslinking agent. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) techniques were used to characterize the prepared hydrogels. Their swelling behaviours were investigated according to the maleic acid content and pH of solution. Kinetic swelling of hydrogels was studied too. The results showed that the swelling ratios increase with increasing the maleic acid content. Kinetic studies showed good fitting to pseudo-second order equation. The prepared hydrogels obeyed non-Fickian water diffusion.