Nitrous oxide (N₂O) emission and absorption and carbon dioxide (CO₂) emission from Eutric Cambisol were measured after treatment soils with NO₃^–-N in laboratory incubation experiments. Incubation experiments were designed to investigate the influence of variables such as oxidation-reduction conditions, pH, organic matter content and granulometric composition on denitrification capacity of investigated soils. Results showed that these soils were emitters (cumulative production N₂O ranged from 11.4 to 66.5 mg N₂O-N kg^–1 of soil) as well as reducers (daily sink of N₂O ranged from 1.3 to 66.5 mg N₂O-N d^–1 kg^–1 of soil). The range of reduction of N₂O under investigation conditions was from 10 to 100% depending on the kind of soil and time of incubation. Production and reduction of N₂O were nonlinearly correlated with redox potential (R² = 0.906 and R² = 0.966, respectively). The boundary value of redox potential for emission of nitrous oxide was 250 m V and for absorption of N₂O was about 200 m V. Redox potential showed a negative correlation with pH value (R² = 0.685). Eh value decreased with decreasing of NO₃^–-N·in the range from about 10 to 100 mg NO₃^–-N kg^–11 of soil. The highest daily reduction of nitrate was observed in the narrow range of Eh value (200-210 mV). The boundary nitrate concentration resulted in distinct drop of redox potential was about 100 mg NO₃^–-N kg^–1. Under investigated conditions the maximum emission of N₂O was observed at pH range between 4.5-6, but maximum absorption of nitrous oxide occurred at pH about 5.5 to about 7. Differences in the dissimilative reduction of nitrate were observed in the investigated soils. Absorption of N₂O occurred simultaneously with the reduction of nitrate and after depletion of NO₃– during the course of the experiment. The range of reduced nitrate fluctuated from 22 to 100% depending on the kind of soil and time of incubation. Denitrification rate and sink of nitrous oxide showed high correlation with mineralization of organic matter (R² = 0.906 and R² = 0.913, respectively). Daily emission of CO₂ ranged from 1.3 to 23.2 mg CO₂-C kg^–1 d^–1 and was correlated with redox potential (R² = 0.871), organic matter content (R² = 0.314), and pH (R² = 0.804). Differences in release of CO₂ were 132 noticed in the investigated soils. The lowest cumulative amount of carbon dioxide was found in soils developed from sand (mean 75 mg CO₂-C kg^–1). Higher emission was observed in soils developed from loam (mean 130 mg CO₂C kg^–1) and the highest amount of carbon dioxide was obtained in soils developed from silt (mean 210 mg CO₂-C kg–1). Relationship between carbon (as CO₂) and nitrogen (as N₂O) flux reflected by the C/N ratio in the headspace air and relationship between carbon (as CO₂ flux) and nitrogen (as NO₃^– reduced) were calculated. These two ratios describe the character of biochemical processes in the soils particularly their denitrification capacity as well as their ability to sink of nitrous oxide and nitrate reduction.