This paper describes a real‐time speckle interferometer specially designed to measure the thermal expansion of a large class of intermetallic compounds for which surface optical treatments are difficult or even impossible. The instruments’ 5% accuracy, experimentally checked over the range 300–900 K, makes it a more accurate and cheaper alternative to the x‐ray devices commonly used for the above‐mentioned compounds. Moreover, the extreme simplicity of the optical setup allows an almost immediate alignment procedure and therefore makes the instrument suitable for routine measurements. The advantages of simultaneous measurements in different spots of the sample surface are also outlined. A comparison with standards, together with the measured expansion anomaly of an intermetallic compound (Ce24Co11) are presented.