A mathematical description of the hyperbolic tangent distribution function family is presented which serves as convenient means to characterise particle size distributions in particulate disperse systems. Analytical formulae are given for the calculating the mean and standard deviations of the cumulative distribution function are given. A number of approximate expressions, including interpolating formulae, are developed and discussed for computing the hyperbolic tangent distribution functions from discrete - experimental - data. A method is shown fitting of hyperbolic tangent distribution function to experimental data of particle size distributions. This method call be utilised as a convenient means to identify the mathematical models of particulate processes.