Thermogravimetric analysis[1][2]​ or thermal gravimetric analysis (TGA) is a method of thermal analysis in which the mass of a sample is measured over time as the temperature changes. This measurement provides information on physical phenomena, such as phase transitions, absorption, adsorption and desorption; as well as chemical phenomena including chemical reactions, thermal decomposition and solid gas reactions (for example, oxidation or reduction "Reduction (chemistry)")).

Thermogravimetric analysis (TGA) is performed on an instrument called a thermogravimetric analyzer. A thermogravimetric analyzer continuously measures mass as the temperature of a sample changes over time. Mass, temperature, and time in thermogravimetric analysis are considered baseline measurements, while many other quantities can be derived from these baseline measurements.

A typical thermogravimetric analyzer consists of a precision balance with a sample tray located inside an oven with a programmable control temperature. The temperature is generally increased at a constant rate (or, in some applications, the temperature is controlled for a constant mass loss) to incur a thermal reaction. The thermal reaction can occur under a variety of atmospheres including: ambient air, vacuum, inert gas, oxidizing/reducing gases, corrosive gases, fuel gases, liquid vapors, or "self-generated atmosphere"; as well as a variety of pressures including: high vacuum, high pressure, constant pressure or controlled pressure.

Thermogravimetric data collected from a thermal reaction are compiled into a graph of initial mass or percent mass on the y-axis versus temperature or time on the x-axis. This graph, which is often smoothed, is known as a TGA curve. The first derivative of the TGA curve (the DTG curve) can be plotted to determine inflection points useful for in-depth interpretations as well as differential thermal analysis.

A TGA can be used for material characterization through the analysis of characteristic decomposition patterns. It is an especially useful technique for the study of polymeric materials, including thermoplastics, thermosets, elastomers, composites, plastic films, fibers, coatings, paints and fuels.

Thermal conductivity (often expressed as k, λ, or κ) refers to a material's intrinsic ability to transfer or conduct heat. It is one of three methods of heat transfer, the other two being: convection and radiation. Heat transfer processes can be quantified in terms of the corresponding rate equations. The rate equation in this mode of heat transfer is based on Fourier's law of heat conduction.