Yes, it is deductible !
In 2019, you are entitled to deduct 14c for every mile you did for volunteer work. Have you kept records of what you did and the location of the work ?
In addition, he cost of travel, such as air, rail, and bus transportation, as well as meals and lodging, are deductible while away from home doing volunteer work if there is no significant element of personal pleasure, recreation, or vacation in the travel. The deduction will not be denied simply because you enjoy doing the volunteer work. However, if you have only nominal duties for the charity, or if for significant parts of the trip you do not have duties to perform, the travel expenses are not deductible.
So if you did not keep good records for 2019 or it is too difficult to recreate 2019 records then please make sure that you start your 2020 recordkeeping today. And this doesn’t have to be anything fancy. There are apps you can use but a good old fashioned notebook works too.