We present spectroscopic observations with the 3.6m ESO telescope of two emission-line galaxies , J2104 - 0035 and J0113 + 0052 , selected from the Data Release 4 ( DR4 ) of the Sloan Digital Sky Survey ( SDSS ) .
From our data we determine the oxygen abundance of these systems to be respectively 12 + log O/H = 7.26 \pm 0.03 and 7.17 \pm 0.09 , making them the two most metal-deficient galaxies found thus far in the SDSS and placing them among the five most metal-deficient emission-line galaxies ever discovered .
Their oxygen abundances are close to those of the two most metal-deficient emission-line galaxies known , SBS 0335–052W with 12 + log O/H = 7.12 \pm 0.03 and I Zw 18 with 12 + log O/H = 7.17 \pm 0.01 .