We have prepared the oxyhydrate Na 0.3 RhO 2 ·0.6H 2 O by extracting Na + cations from NaRhO 2 and intercalating water molecules using an aqueous solution of Na 2 S 2 O 8 . Rietveld refinement, thermogravimetric analysis (TGA), and energy-dispersive X-ray analysis (EDX) reveal that a non-stoichiometric Na 0.3 (H 2 O) 0.6 network separates layers of edge-sharing RhO 6 octahedra containing Rh 3+ (4d 6 , S=0) and Rh 4+ (4d 5 , S=1/2). The resistivities of NaRhO 2 and Na 0.3 RhO 2 ·0.6H 2 O (T<300) reveal insulating and semi-conducting behavior with activation gaps of 134 and 7.8meV, respectively. Both Na 0.3 RhO 2 ·0.6H 2 O and NaRhO 2 show paramagnetism at room temperature, however, the sodium-deficient sample exhibits simultaneously a weak but experimentally reproducible ferromagnetic component. Both samples exhibit a temperature-independent Pauli paramagnetism, for NaRhO 2 at T>50K and for Na 0.3 RhO 2 ·0.6H 2 O at T>25K. The relative magnitudes of the temperature-independent magnetic susceptibilities, that of the oxide sample being half that of the oxyhydrate, is consistent with a higher density of thermally accessible electron states at the Fermi level in the hydrated sample. At low temperatures the magnetic moments rise sharply, providing evidence of localized and weakly-ordered electronic spins with effective moment per formula unit values of 2.0×10 −1 μ B for NaRhO 2 and 0.8×10 −1 μ B for Na 0.3 RhO 2 ·0.6H 2 O.