The influence of different solvents on the extraction ability of aliphatic non - chelating aldoximes with respect to CuCl2, NiCl2and CoCl2has been investigated with heptanaloxime as an example. The effect of carbon tetrachloride, toluene, chloroform, 1,2-dichloroethane, caprylic acid on syn-antiisomerization and aggregation of heptanaloxime has been studied and the constants of these processes have been calculated. It has been shown also it was aldoxime anti - isomer that formed the extracted complex with metals. The equation of state of non-chelating aldoximes in the extraction systems has been deduced.