A profound comprehension of how the pyrolysis process is influenced by thermodynamic conditions is essential for improving the efficiency of biofuel production systems. Numerous research articles are devoted to the experimental investigation of pyrolysis performed using laboratory scale-devices. Some of them include numerical models validated by these experimental data. However, due to the small scale, in most works, the role of energy is neglected and minimized to the rate of heating, despite that it is thermal energy that initiates and controls thermal decomposition processes. This work presents a transient two-dimensional model of biomass wooden particle pyrolysis consisting of energy balance and two mass conservation equations. Explicit numerical methods are used in order to compromise the high computing power requirements for 2D transient simulation. The model consists of a set of three equations. The first equation is a solid mass conservation equation in a standard form for pyrolysis modelling, including the reaction rate constant described with Arrhenius equation. Additionally, water (moisture) mass loss equation was implemented, using moisture evaporating flux based on the water saturation pressure function. The energy balance equation includes heat transfer due to conduction and source terms describing the pyrolysis gasses and moisture leaving the control volume. The non homogenous structure of wood is embodied in the model with the use of two different thermal conductivity coefficient, depending on the direction. According to the literature data, a higher thermal conductivity coefficient was applied in the direction perpendicular to the wooden fibers, and 2.5 times lower in the direction parallel with the fibers. The simulated particle geometry is a square, with wall length of 2 cm. The control volume method and an explicit numerical scheme were used to solve the described equation system. An in-house code was developed and executed using the Fortran language. The simulated sample was set to be at 300 K (initial condition) with 800 K at the wall (boundary condition). The process was conducted until the decomposition processes stopped (after `900 s). The proposed model can be used for relatively fast simulations of pyrolysis processes in 2D with low requirement for computing power simulation. Furthermore, the anisotropy of wood considered in the proposed model was clearly visible in the results.