Patent ID: 7727930

Claim:
A catalyst having a composition represented by the following formula (3), satisfying the following equations (4) and (5) in X-ray photoelectron spectrometry (XPS), and having a peak derived from a metal bond of a T1 element which is shown in an XPS spectrum: Pt x Ru y T1 a X1 b (3) wherein the T1 element is at least one element selected from the group consisting of V, W and Mo, an X1 element is at least one element selected from the group consisting of Nb, Cr, Zr and Ti, x is 20 to 70 at. %, y is 10 to 50 at. %, a is 1 to 30 at. % and b is 0.5 to 20 at. %; 0≦(C oxygenT1 /C metalT1 )≦4 (4) 0≦(C metalX1 /C oxygenX1 )≦2 (5) wherein C oxygenT1 is an amount of the Ti element having an oxygen bond which is obtained by the XPS spectrum, C metalT1 is an amount of the T1 element having a metal bond which is obtained by the XPS spectrum, C metalX1 is an amount of the X1 element having a metal bond which is obtained by the XPS spectrum, and C oxygenX1 is an amount of the X1 element having an oxygen bond which is obtained by the XPS spectrum.