Hydrogen peroxide in its reaction with KIO4 and NH2OH respectively is acting as:

KIO4 + H2O2 → KIO3 + H2O + O2

In this reaction, hydrogen peroxide (H2O2) reduces KIO4 to KIO3, while itself gets oxidized to O2. Therefore, H2O2 acts as a reducing agent in this reaction.

In the reaction with NH2OH, hydrogen peroxide oxidizes NH2OH. The exact products depend on the reaction conditions, but a possible reaction is:

H2O2 + NH2OH → HNO2 + 2H2O

Here, hydrogen peroxide (H2O2) oxidizes hydroxylamine (NH2OH) to nitrous acid (HNO2), while it itself gets reduced. Therefore, H2O2 acts as an oxidizing agent in this reaction.

Hence, hydrogen peroxide acts as a reducing agent with KIO4 and an oxidizing agent with NH2OH.