The new oxide and oxyhydrate NaRuO2 and NaxRuO2.yH(2)O (X = 0.22, y = 0.45) have been characterized. NaRuO2 is isostructural with alpha-NaFeO2. The symmetry is rhombohedral (R (3) over barm space group) with lattice parameters of a = 3.018(2) Angstrom and c = 16.493(3) Angstrom. The structure has been refined by the Rietveld method. The oxyhydrate NaxRuO2.yH(2)O has been prepared by stirring a sample of NaRuO2 in water at ambient temperature. NaxRuO2.yH(2)O crystallizes in the space group R (3) over barm with lattice parameters of a = 2.930(2) Angstrom and c = 21.913(5) Angstrom. The structure is related to the CuFeO2 3R polytype structure with the AABBCC sequence of the oxygen close packed layers along the c-axis. Analogies with the related cobalt phases are discussed. The susceptibilities of NaRuO2 and NaxRuO2.yH(2)O are small and constant in a large temperature range.