An oxidising agent is a substance which

An oxidising agent (or oxidant) is a substance that causes the oxidation of another species by accepting electrons from it [t2, t9]. In a redox reaction, oxidation is defined as the loss of electrons, which results in an increase in the oxidation number of the element being oxidised [t1, t4, t5]. Therefore, the oxidising agent facilitates this process, effectively increasing the oxidation number of an element in the given substance [t1]. Conversely, the oxidising agent itself gains electrons and undergoes reduction, meaning its own oxidation number decreases [t2, t3]. While classical definitions describe oxidising agents as substances that add oxygen or remove hydrogen [c3], the modern electronic definition focuses on electron transfer and the subsequent increase in the oxidation state of the target substance [t1, t6].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Formation of coal and petroleum > p. 71