I see no wattles, so I'd *guess* female? a close up shot of the comb, from the front, would be helpful. Also knowing the breed for sure would help.
Also, if it's a barred rock, the females are darker. That's pretty dark, so if it is a barred rock (and that' would be my guess if it's got a single comb) I'd say female.
If it's a black sex link then it's for sure a male.