In the alumino-thermic process, aluminum acts as

Alumino thermic process is an exothermic process in which aluminum is used as a reducing agent at high temperatures. This process is used for the production of iron alloys. 

For example the reaction between iron oxide and aluminum to produce iron.
$F{e}_2{O}_3+2\mathit{Al }\to \mathit{ A}{l}_2{O}_3+2\mathit{Fe}$

Hence, in the alumino-thermic process, aluminum acts as a reducing agent.