Calcium (Ca) dynamics between casein micelles (CM) and serum phase (SP) in pasteurised skim milk were characterised by temperature dependence (4-35 degrees C) of Ca partition between phases and rate of formation of ionic calcium (Ca2+) in SP. Increase in Ca2+ during storage was characterised by two kinetic models: (1) 4-20 degrees C, with two parallel first order reactions, a fast dominating for first 3 h and a slower between 3 and 8 h, negative energies of activation (-22 kJ mol-1 and -48 kJ mol-1, respectively) explained by endothermic binding of Ca2+ to CM for the slow reaction and by endothermic Ca2+ binding to ligands in SP; (2) 4-35 degrees C, decrease in rate of Ca2+ formation with increasing temperature assigned to reversible endothermic association of serum Ca2+ to phosphate and 3-casein. 3-Casein release from CM decreased like Ca2+, suggesting interaction between 3-casein and Ca2+ during transfer from CM to SP.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).