Can I use a cooling rack in the oven?

Only if it's rated as oven safe check the product listing. Stainless steel racks are generally safe up to 500°F. Non stick coated racks are usually safe up to 450°F. Chrome plated racks vary. Never put bamboo, plastic, or silicone footed racks in the oven. When used in the oven on a sheet pan, racks elevate food for crispier results great for bacon, roasted vegetables, and breaded items.