The physico-chemical water characteristics and basin morphology of 10 well-preserved Pomeranian peatland lakes were examined. These are acidic (pH 3.95 -5.99), softwater (1.5 ±0.9 mg Ca dm -3 ), and oligotrophic water bodies. Their hydrochemical conditions differentiate them into two groups: poor (3.04 ±2.77 mg C dm -3 ) and rich (10.36 ±7.27 mg C dm -3 ) in organic carbon compounds. They differ in water colour (p = 0.02), humic acid concentration (p<0.001), redox potential (p = 0.007), and irradiance (PAR; p = 0.03).The hydrochemistry of the lakes is determined by their basin morphology, which affects the water colour and the concentrations of humic acids and organic carbon compounds.