The sensitivity of NH3-SCR activity to water vapour at 70 degrees C is tested for Cu/SAPO-34 (morph.) catalysts. The synthesised Cu/SAPO-34 (morph.) is remarkably susceptible to low-temperature activity loss. After only 3 hat 70 degrees C, the NOx conversion decreases from an initial 87% to 66% at 200 degrees C, after another 9 h to 6%. This deactivation is accompanied by a partial loss of microporous volume, but the SAPO-34 framework remains crystalline. We postulate that a transformation of the active copper sites into an inactive form could be the cause for the deactivation. Regeneration of the catalyst was attempted, but had no impact on activity. (C) 2014 Elsevier B.V. All rights reserved.