We calculate the effective temperature ( T _ { eff } ) of ionizing star ( s ) , oxygen abundance of the gas phase ( O / H ) , and the ionization parameter U for a sample of H ii regions located in the disks of 59 spiral galaxies in the 0.005 \ > < \ > z\ > < \ > 0.03 redshift range .
We use spectroscopic data taken from the CALIFA data release 3 ( DR3 ) and theoretical ( for T _ { eff } and U ) and empirical ( for O/H ) calibrations based on strong emission-lines .
We consider spatial distribution and radial gradients of those parameters in each galactic disk for the objects in our sample .
Most of the galaxies in our sample ( \sim 70 % ) shows positive T _ { eff } radial gradients even though some them exhibit negative or flat ones .
The median value of the T _ { eff } radial gradient is 0.762 kK/ R _ { 25 } .
We find that radial gradients of both \log U and T _ { eff } depend on the oxygen abundance gradient , in the sense that the gradient of \log U increases as \log ( O / H ) gradient increases while there is an anti-correlation between the gradient of T _ { eff } and the oxygen abundance gradient .
Moreover , galaxies with flat oxygen abundance gradients tend to have flat \log U and T _ { eff } gradients as well .
Although our results are in agreement with the idea of the existence of positive T _ { eff } gradients along the disk of the majority of spiral galaxies , this seems not to be an universal property for these objects .