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The magnetic record, preserved by igneous rocks in the form of thermoremanent magnetization (TRM) or thermo‐chemical remanent magnetization (TCRM), is essential to reconstruct Earth's absolute paleointensity (API) but strongly depends on the kinetic conditions in which the remanence was acquired. In this paper, we present exact analytical solutions describing the time‐dependent processes of acquisition and thermal demagnetization of various kinds of thermally activated remanences for non‐interacting single‐domain grains with uniaxial shape anisotropy. Our solutions, derived in less‐restrictive conditions than previous studies, are also valid for TCRMs acquired either by growth of grain volume or by increase of the Curie point T_c. We first show that TCRMs by T_c increase and TRMs are of comparable intensity whereas TCRMs by volume growth are significantly less intense. We then model Arai‐Nagata …