What documents do I need to file for benefit from an ex-spouses social security?

Q) What documents do I need to file to collect social security benefit from an ex-spouses social security?

A) According to Social Security Administration You can apply for benefits by calling our national toll-free service at 1-800-772-1213 (TTY 1-800-325-0778) or visiting your local Social Security office. An appointment is not required, but if you call ahead and schedule one, it may reduce the time you spend waiting to apply.

You can help by being ready to:

Provide any needed documents; and
Answer the questions listed below.
Documents You may need to provide

SSA may ask you to provide documents to show that you are eligible, such as:

Proof of the worker’s death;
Birth certificate or other proof of birth;
Proof of U.S. citizenship or lawful alien status if you were not born in the United States [More Info];
U.S. military discharge paper(s) if you had military service before 1968;
U.S. military discharge paper(s)
For disability benefits, the two forms (SSA-3368 and SSA-827) that describe your medical condition and authorize disclosure of information to us;
W-2 forms(s) and/or self-employment tax returns for last year;
Final divorce decree, if applying as a surviving divorced spouse; and
Marriage certificate

http://www.socialsecurity.gov/online/ssa-10.html