The diffusion coefficients of small paramagnetic tracers (nitroxide spin probes) and spin-labeled poly(ethylene oxide) in hydrogels were measured at 300 K, using two-dimensional spatial-spectral ESR imaging (ESRI). The gels were prepared by copolymerization of 2-hydroxyethyl methacrylate (HEMA) and 2-(2-hydroxyethoxy)ethyl methacrylate (DEGMA), in the presence of a fured molar concentration of glycol dimethacrylate as the cross-linker and 4,4’-azobis(4-cyanopentanoic acid) as the initiator. Variation of the amount of water in equilibrium with the gel was achieved by polymerizing different molar ratios of the monomers. Experimental concentration profiles of the diffusant were measured as a function of time, and each profile was obtained by image reconstruction, from a complete set of projections. The diffusion coefficients were determined by simulating all experimental profiles, using the Fick model of diffusion for an initially confined tracer diffusing into a finite system. The diffusion coefficients depend on the amount of water in the gels. The variation of the diffusion coefficients D with the weight fraction of the copolymer in the gel is consistent with the free volume model. The variation of D with the molecular mass M of the diffusant scales as M(-0.8) in gels containing greater than or equal to 67 wt% water and as M(-1.4) for the gel containing 55 wt% water. The advantages and present limitations of 2D spatial-spectral ESRI for measuring transport properties in polymers are discussed.