OilProp is designed to assess the core thermalphysic properties of oil and its derivatives necessary to solve transportation and processing tasks, with the minimum volume of input data. It is based on regularities and statistics generally known in the area. OilProp solves the following tasks: 1. Basic Calculation - calculation of thermalphysic properties at the atmosphere pressure and the temperature 20 deg.C (68 deg. F).The calculation results are used for hydraulic analysis of pipelines as well as in design of equipment intended for storage, thermostating, transportation, mixing, spraying homogenization of oil and its derivatives. Density and / or fractional composition of the substance are used as input data (the calculation is more precise if fractional composition is given). The program calculates density (if not given), isobaric specific heat, thermal conductivity, kinematic viscosity, average saturated vapor pressure, surface tension, the Prandtl number, and pseudocritical temperature. 2. Additional Calculation - calculation of thermalphysic properties of a substance in liquid and gas phases at given absolute pressure and temperature within the under-critical range. The calculation results are used for process modeling and design of equipment intended for processing of oil and its derivatives, for hydraulic and aerodynamic design of pipelines at steady and non-steady temperature, as well as to find out heat exchange process characteristics, etc. Additional input data, besides temperature and pressure, are density and/or fractional composition (calculation is more precise when fractional composition is given). The program calculates the percentage of liquid and gas phases, density, isobaric heat, thermal conductivity, vaporization enthalpy, kinematic viscosity, surface tension (for the liquid phase only), and the Prandtl number.