In this paper, an analytical model is established to describe the deposition kinetics and the deposition chamber characteristics that determine the deposition rates of pure boron (PureB-) layers grown by chemical-vapor deposition (CVD) from diborane (B2H6) as gas source on a non-rotating silicon wafer. The model takes into consideration the diffusion mechanism of the diborane species through the stationary boundary layer over the wafer, the gas phase processes and the related surface reactions by applying the actual parabolic gas velocity and temperature gradient profiles in the reactor. These are calculated theoretically and also simulated with fluent software. The influence of an axial and lateral diffusion of diborane species and the validity of the model for laminar flow in experimental CVD processes are also treated. This model is based on a wide range of input parameters, such as initial diborane partial pressure, total gas flow, axial position on the wafer, deposition temperature, activation energy of PureB deposition from diborane, surface H-coverage, and reactor dimensions. By only adjusting these reactor/process parameters, the model was successfully transferred from the ASM Epsilon One to the Epsilon 2000 reactor which has totally different reactor conditions. The model's predictive capabilities have been verified by experiments performed at 700°C in these two different ASM CVD reactors.