In the rules of game it says:

If a hero attacks without
a weapon, he attacks
with his fists. This is a
melee attack that grants
one red die and has no
special abilities.

Also in the rules says that: When a hero makes a melee attack, he adds a number of power dice to his roll equal to his melee trait.

So when a hero makes an unarmed attack he should add the power dice right?

What about One-Fist's ability, could he add the power dice in his extra attack?

thx and by3z!

Yes and yes.

But note that neither unarmed nor hook attacks are able to spend surges (except special situations eg with the Gauntlets of Power from AoD)

I believe you can attack with your fists and use your melee power dice. I also think you can add power dice with fatigue.

Thanks both, maybe in the english rules sounds more clear, but we are discussing this topic at the spanish forum and we don't agree.

I agree with the two posts above you: you do add the power dice noted in your melee trait even when fighting with just your fists. Treat One Hook's extra attack as any normal attack with a weapon: all rules on adding power dice via Fatigue can be applied to it.