The conversion of ethanol to ethanoic acid involves the removal of the Hydrogen atom and the addition of oxygen (oxidation reaction).

In the first step, the Hydrogen molecule is removed from ethanol to form ethanal.

Since Hydrogen loss is oxidation so, the reaction is an oxidation reaction.

Similarly an oxygen atom is added to form ethanoic acid from ethanal. As, the gain of Oxygen is called oxidation.

So, the reaction is an oxidation reaction.