The thermal behaviour of danburite-like phases MB2Si2O6 (M = Ca, Sr, Ba) has been studied by in situ high temperature x-ray powder diffraction and heat treatments in a wide temperature range using a natural danburite (Ca) sample and synthetic samples of pekovite (Sr) and maleevite (Ba). Synthetic pekovite was obtained by solid state reactions at 900°C, whereas synthetic maleevite was synthesised by crystallisation from the melt. According to the high temperature x-ray powder diffraction study, the Ca, Sr, and Ba members of the danburite group demonstrate a weak anisotropy of thermal expansion with relatively low volume thermal expansion coefficients (19, 20, and 23×10–6 °C−1, respectively). Both thermal expansion coefficients and the expansion anisotropy increase with increasing size of the M2+ cations.