A new type of measuring apparatus for hydrogen permeation has been developed based on coulometric titration utilizing the electrochemical cell : (ref.:-)Pt, Ar+1% H-2/CaZrO3(+In2O3)/Ar+H-2, Pt(+:mes.). This is a modified apparatus of the hydrogen analyzer developed previously by the present authors. A very small permeation of hydrogen (to the order of 10(-12) mol/s(H-2)) could be measured by this apparatus. A permeability of hydrogen of silica glass was measured at temperatures between 773 and 1073 K. The measured values were close to the previous values reported by Lee et al.