Your situation is somewhat of a "hot topic" in tax law.
Several years ago, the answer to your question would be a "no" that you cannot deduct something that you did not pay or for which you were reimbursed later.
However, now the answer is a "maybe."
There was a ruling in the Judith Lang case that allowed Ms. Lang to deduct expenses because the amount she received to pay the medical bills was a "gift" ( http://www.ustaxcourt.gov/inophistoric/la5ng.tcm.wpd.pdf )
Ms. Lang's mother paid her medical expenses and real estate taxes. Ms. Lang was not a minor. The Tax Court ruled that in effect the amount was a gift to the daughter, and deductible by the daughter as if she had paid it herself.
A key point in the case was “petitioner [Judith Lang] was not a minor, and Mrs. Field [Judith Lang’s mother] was not legally obligated to pay petitioner’s expenses.” If Mrs. Field was obligated to pay the expenses, then her daughter may not have been able to deduct them, as they wouldn’t have been a gift.
Like your situation, you are not a minor (I assume) and the organization had no obligation to pay on your behalf.
Unlike your situation, the mother, in that case, paid directly to the hospital which your organization did not.
Would the IRS and tax court see your situation the same? No one can be sure, so if you deduct the expenses and get audited then you would have to try to make the comparisons between your case and that one that the money from the charity was a gift. Then you may need to pay taxes on the gift which is a whole different issue.
