That gets tricky, but I think it can be done indirectly. I doubt airlines will let you directly transfer miles to a charity, but you could inform a charity that you will use your personal miles to get awards for the charity. When the charity needs to get some air travel (e.g., school principal needs to attend a conference), you could get a mileage award for the charity's employee, and deduct the fair market value of the miles.

However, this gets complicated if the source of your miles is business travel (travel as an employee or business travel for the self-employed). Then you have a zero cost basis for the miles. That might not be a problem if you've held the miles for more than a year.

In short, to deduct the value of a mileage award you need to put some thought into this, and you need to be prepared for questions from the IRS. And you need to disregard the unhelpful advice someone inevitably gives about how the IRS declared that miles have no value. The IRS did no such thing, as I've explained on FT several times.