Verification of the codes that provide numerical heat transfer solutions obtained by finite difference and other methods is important. One way to verify these solutions is to compare the values with exact solutions. However, these exact solutions should also be verified. Fortunately, intrinsic verification methods are possible. Intrinsic verification utilizes at least two independent exact solutions to obtain accurate numerical values. Three different types of intrinsic verification for transient and steady state heat conduction are developed and illustrated by examples. (c) 2006 Elsevier Ltd. All rights reserved.