The present invention relates to a method of forming a paraffinic product that involves providing a paraffinic feed having an initial average carbon chain length of greater than 20. The paraffinic feed is a product of a gas-to-liquids process, such as a Fischer-Tropsch process. The paraffinic feed is subjected to thermal cracking at elevated temperature and elevated pressure, which results in the formation of a paraffinic product. The paraffinic product has a final average carbon chain length of less than or equal to 20. The paraffinic product is typically liquid at ambient temperature, such as at 25° C.