The French international was signed on a free transfer earlier this summer from Auxerre and started the Gunners' 2-1 defeat to Turkish champions Galatasaray at the weekend.
Having spent the summer on international duty with France with whom he won the U20 World Cup, Wenger is pleased with Sanogo's display.
"Yes [I was pleased with him]," Wenger told the club's official website.
"Considering he just came back from holiday and only had three or four days of practice, what he did is encouraging."
Sanogo was replaced in the second half of the match by Olivier Giroud.