Controlled chemical transformation of water vapor in dielectric barrier discharge (DBD) of argon into hydrogen and hydrogen peroxide for its usability as in situ or ex situ H-2 and H2O2 source are reported. Online analysis of the product gas mixture by conventional wet-chemical colorimetric method using buffered KI absorber solution revealed typical H2O2 G-value = 6.4 x 10(-3) A mu mol J(-1) (G-value defines as the number of molecules produced/consumed per 100 eV of energy; in SI unit G-value is expressed in A mu mol J(-1)) in the absence of ozone. On the other hand, H-2 in product mixture analyzed in gas chromatograph-thermal conductivity detector (GC-TCD) with argon carrier revealed its G-value = 0.134 A mu mol J(-1). Enhancements in products' yields were explored by varying gas residence time inside the plasma zone, and applied voltage and frequency on the dielectric surfaces. Employing a double-DBD reactor, at applied high voltage similar to 2.5 kV mm(-1) @50 Hz and gas residence time similar to 20 s resulted in the highest yields of H2O2. However, the H-2 yield increased continuously with increase in gas residence time. On the other hand, the single-dielectric barrier surface reactors were more efficient for high and exclusive generation of ex situ H-2 (e.g. maximum 1260 ppm; G-value typically 0.498 mu mol J(-1)).