Journal of Molecular Catalysis A: Chemical publishes full papers that are original, rigorous, and scholarly contributions examining the molecular and atomic aspects of catalytic activation and reaction mechanisms in homogeneous catalysis, heterogeneous catalysis (including supported organometallic catalysis) and computational catalysis. The Journal also publishes timely reviews of specialized topics within the scope outlined above, however prospective authors must obtain preliminary approval from the Editor-in-Chief before preparing such an article. Accepted manuscripts of exceptional quality and substantial interest to the readership may be selected by Editors to feature in the 'Editors Choice' section of the Journal. Contributions that do not fall within the above aims and scope will be rejected at the editorial level. Examples of papers falling into this category are those for which the major focus is on preparative inorganic chemistry and associated structural characterisation, on polymer characterisation, or on the synthetic organic applications of catalysis, rather than the molecular and atomic aspects of catalytic activation and reaction mechanism. In keeping with the aims and scope of the journal, it is expected that catalyst activity be appropriately expressed. Thus, homogeneous systems are ideally characterised by kinetic analysis from which macro- or micro-scopic rate constants can be presented. At the very minimum, turnover number and frequency should be reported. For heterogeneous catalysis, activity should ideally be expressed in turnover frequencies per site or at least per unit area of active component measured using an appropriate method, such as chemisorption or estimated from the particle size obtained by such techniques as transmission electron microscopy or XRD line-broadening. Extensive use of percent conversion should be avoided. Since the scopes of the Elsevier journals Journal of Molecular Catalysis A: Chemical, Journal of Molecular Catalysis B: Enzymatic, Applied Catalysis A: General, Applied Catalysis B: Environmental, and Catalysis Communications are complementary, an appropriate submission to each journal could be borderline, in which case the advice of another Editor will be sought, possibly redirecting the submission to either Journal of Molecular Catalysis B: Enzymatic, Applied Catalysis A: General, Applied Catalysis B: Environmental, or Catalysis Communications (for letters) with the author(s)'s agreement.