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• Spray-dried camel milk powders were stored at 11–33% RH (37 °C) over 18 weeks. • An increase in surface lipid caused an increase in surface hydrophobicity. • Wettability was not affected, and dispersibility and solubility dropped during storage. • There was a strong correlation between surface lipid content and powder solubility. • Powder property changes were more profound at 33% RH than at lower RH levels. Alterations in surface chemical composition relating to rehydration properties of spray-dried camel milk powders during accelerated storage (11–33% RH, 37 °C) over 18 weeks were investigated. The results showed that the surface of the fresh spray-dried camel milk powder (t = 0) was dominated by lipids (78%), followed by proteins (16%) and lactose (6%). During storage, the surface protein and lactose content decreased while the surface lipid content increased, resulting in an increase in surface hydrophobicity and slight agglomeration of the powder, especially for powder kept at 33% RH. Although fresh camel milk powder had very poor wettability, it displayed very high dispersibility and solubility (99%). During storage, dispersibility and solubility declined with increasing storage time and increasing RH levels, which correlated with an increase in surface lipid content. However, at the end of the storage period, camel milk powder still retained very high solubility (>93%). [ABSTRACT FROM AUTHOR]