This study describes the development of a 1D dynamic thermal finite difference model for rotational moulding. In this process, loosely packed powder particles are heated in a rotating mould. As the temperature increases, the particles start to adhere to the mould wall and sinter until a fully densified polymer melt is formed. The objective of this study is to acquire more fundamental knowledge on this deposition and sinter process. A uniaxially rotating cylindrical geometry is modelled as 2D plane in which deposition, sintering and heat transfer takes place in orthogonal direction. To take into account the continuously changing thermal boundary conditions (powder vs non-powder contact) a powder bed is shifting periodically across the plane. The powder bed contact time is linked to the remaining powder bed volume. The powder bed and air are treated as one lumped mass. The main difference of this model compared to the models found in the literature is the discretisation of the deposition and the incorporation of the dependency of thermal parameters (density and thermal conductivity) on the degree of coalescence. In order to validate this thermal model, dedicated experimental equipment was developed. This equipment allowed monitoring wall and internal air temperatures as well as visualising different types of powder flow. The experimentally measured time-temperature data are in good agreement with the numerically modelled data and allow to gain fundamental knowledge on rotomoulding processes.