This contribution to the Festschrift relates to one of Marie-Theresa Mackowsky's 'industrial interests', heating rate, but it is not solely focussed within the field of industrial coking. One intention is to stress the importance of heating rate in the natural environment to illustrate its broad pervasiveness. First discussed, however, are the effects of heating rate on the appearance, optical properties and molecular structures of organic matter in laboratory experiments, before considering instances of the influence of heating-rate variation on sedimentary organic matter within the natural environment. Notable illustrations within igneous provinces in the Midland Valley of Scotland and North-east England are described. Heating rate is obviously only one of a number of factors involved in the ultimate development of coal rank or level of organic metamorphism, but the instances cited here emphasize that heating rate is not only an important factor in industrial carbonisation but is also a widely effective contributor to the variable maturation of crustal organic matter. (c) 2006 Elsevier B.V. All rights reserved.