Hi!

Thanks for your question.

Although this is most likely safe to toast marshmallows, we would advise against it. It has never been tested for this application and marshmallow debris may enter the fuel can and cause a dangerous environment.

This fireplace uses a 13 oz. can of gel fuel that can be found in big box stores in certain areas and is abundantly available online. We recommend the Sunjel brand.

We hope that this has answered your question. Should others arise, please feel free to reach out again.