* 1848 – William Thomson extends the concept of absolute zero from gases to all substances
* 1849 – William John Macquorn Rankine calculates the correct relationship between saturated vapour pressure and temperature using his hypothesis of molecular vortices
* 1850 – Rankine uses his vortex theory to establish accurate relationships between the temperature, pressure, and density of gases, and expressions for the latent heat of evaporation of a liquid; he accurately predicts the surprising fact that the apparent specific heat of saturated steam will be negative
* 1850 – Rudolf Clausius coined the term "entropy" (das Wärmegewicht, symbolized S) to denote heat lost or turned into waste. ("Wärmegewicht" translates literally as "heat-weight"; the corresponding English term stems from the Greek τρέπω, "I turn".)
* 1850 – Clausius gives the first clear joint statement of the first and second law of thermodynamics, abandoning the caloric theory, but preserving Carnot's principle
* 1851 – Thomson gives an alternative statement of the second law
* 1852 – Joule and Thomson demonstrate that a rapidly expanding gas cools, later named the Joule–Thomson effect or Joule–Kelvin effect
* 1854 – Helmholtz puts forward the idea of the heat death of the universe
* 1854 – Clausius establishes the importance of dQ/T (Clausius's theorem), but does not yet name the quantity
* 1854 – Rankine introduces his thermodynamic function, later identified as entropy
* 1856 – August Krönig publishes an account of the kinetic theory of gases, probably after reading Waterston's work
* 1857 – Clausius gives a modern and compelling account of the kinetic theory of gases in his On the nature of motion called heat
* 1859 – James Clerk Maxwell discovers the distribution law of molecular velocities
* 1859 – Gustav Kirchhoff shows that energy emission from a black body is a function of only temperature and frequency
* 1862 – "Disgregation", a precursor of entropy, was defined in 1862 by Clausius as the magnitude of the degree of separation of molecules of a body
* 1865 – Clausius introduces the modern macroscopic concept of entropy
* 1865 – Josef Loschmidt applies Maxwell's theory to estimate the number-density of molecules in gases, given observed gas viscosities.
* 1867 – Maxwell asks whether Maxwell's demon could reverse irreversible processes
* 1870 – Clausius proves the scalar virial theorem
* 1872 – Ludwig Boltzmann states the Boltzmann equation for the temporal development of distribution functions in phase space, and publishes his H-theorem
* 1873 - Johannes Diderik van der Waals formulates his equation of state
* 1874 – Thomson formally states the second law of thermodynamics
* 1876 – Josiah Willard Gibbs publishes the first of two papers (the second appears in 1878) which discuss phase equilibria, statistical ensembles, the free energy as the driving force behind chemical reactions, and chemical thermodynamics in general.
* 1876 – Loschmidt criticises Boltzmanns H theorem as being incompatible with microscopic reversibility (Loschmidts paradox).
* 1877 – Boltzmann states the relationship between entropy and probability
* 1879 – Jožef Stefan observes that the total radiant flux from a blackbody is proportional to the fourth power of its temperature and states the Stefan–Boltzmann law
* 1884 – Boltzmann derives the Stefan–Boltzmann blackbody radiant flux law from thermodynamic considerations
* 1888 – Henri-Louis Le Chatelier states his principle that the response of a chemical system perturbed from equilibrium will be to counteract the perturbation
* 1889 – Walther Nernst relates the voltage of electrochemical cells to their chemical thermodynamics via the Nernst equation
* 1889 – Svante Arrhenius introduces the idea of activation energy for chemical reactions, giving the Arrhenius equation
* 1893 – Wilhelm Wien discovers the displacement law for a blackbody's maximum specific intensity