Is it correct to say: "I will do that thing when I will talk to him."?
closed as off topic by Matt Эллен, RegDwighт♦ Jul 6 '12 at 9:36
Questions on English Language & Usage Stack Exchange are expected to relate to English language and usage within the scope defined in the FAQ. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about closed questions here.
It is ungrammatical. In such cases, English expresses the future with the present tense: I will do that thing when I talk to him. It is also unlikely that a native speaker would say I will do that thing. It would normally be I’ll do that.