Abstract The x-ray absorption coefficient for strontium in the K edge region (15.6–17.6keV) is determined on aqueous solution of Sr(NO3)2 in a micrometer cell. A series of absorption spectra of the solution and of solvent is recorded for the thickness of the liquid layer varied stepwise between 1 and 2.5mm. The linear absorption coefficient of Sr and water is determined in a variational procedure whereby small systematic errors of the micrometer setting, of signal detection and of disclination of cell windows are eliminated in one step. The results confirm the data on Sr mass absorption coefficient in some recent tabulations in the smooth regions below the edge and further away from it, but show systematically higher values in the wider energy range above the edge. The tabulated data for water agree with the experiment within 4% in the entire range of measurement.