We present here the last results we obtained on the spatial resolved analysis of the ionized gas of disk-dominated galaxies based on CALIFA data. CALIFA is an ongoing IFS survey of galaxies in the Local Univese (0.005 < z < 0.03) that has already obtained spectroscopic information up to ~2.5re with a spatial resolution better than ~1 kpc for a total number of an statiscal sample of galaxies of different morphological types, covering the CM-diagram up to Mr<−18 mag. With nearly 2000 spectra obtained for each galaxy, CALIFA offer one of the best IFU data to study the starformation histories and chemical enrichment of galaxies. In this article we focus on the main results based on the analysis of the oxygen abundances based on the study of ionized gas in H ii regions and individual spaxels, and their relations with the global properties of galaxies. In summary we have found that: (1) the $\mathcal{M}$-Z relation does not present a secondary relation with the star-formation rate, when the abundance is measured at the effective radius; (2) the oxygen abundance present a strong correlation with the stellar surface density (Σ-Z relation); (3) the oxygen abundance profiles present three well defined regimes, (a) an overall negative radial gradient, between 0.5-2 re, with a characteristic slope of αO/H∼-0.1 dex/re, (b) an universal flatenning beyond >2re and (c) an inner drop at <0.5re which presence depends on the mass. All these results indicates that disk-galaxies present an overall inside-out growth, although with clear deviations from this simple scenario.