What are the heat packs composed of? Barocook USA May 27, 2015 18:34 The heat pack’s active ingredients are Calcium Hydroxide and Sodium Bicarbonate Related articles How do I dispose of the used heat packs? For how long will the heat pack cook my food? Can I drink the water that activated the heat packs? Can I use snow to activate the heat packs? Comments 0 comments Please sign in to leave a comment.