The contribution of radiation to heat transfer in a packed bed of coal during its thermal decomposition in a coke oven chamber has been investigated. The phenomenon was analysed while considering the structure change that the coal experiences. The study focused on the increased role of radiation in the processing stage following coal re-solidification. This is when the macrocracks begin to propagate. A simple fissure development model was proposed to describe the influence of varying textures of coke oven charge on the heat transfer process. The results show that the length of fissures penetrating the coke layer perpendicularly to an oven wall is the main factor affecting heat transport due to radiation. This leads to a significant increase in effective thermal conductivity of the coke layer. The work underlines an anisotropic character of thermal radiation in carbonisation beds. (C) 2017 Elsevier Ltd. All rights reserved.