Here is a sample template you can use to write an acknowledgment letter for an in-kind donation.
To [Recipient name]
Dear, [Recipient name]
On behalf of [Name of organization], I would like to thank you for your generous donation of [Description of items] which we received on [Date]. Here at [Name of organization], we have taken the responsibility to [Mission] that we could never fulfill without the help of donors like yourself.
Your generosity will not be overlooked as it will make a positive impact on many people. We value your contribution and wish to fulfill our mission in the most efficient way. This is possible only with your help.
Thanking you again for your aid to this organization.
[Name of organization]