The fluxes of chemical active particles in the effluent of plasma jets are very important parameters for different applications. Herein, we present a method of measurement and an algorithm to obtain plasma parameters and particle fluxes from the atmospheric pressure direct current (dc) plasma jet operated in nitrogen/oxygen mixtures. We determine the atom and radical steady state densities and particles fluxes by means of emission spectroscopy and numerical modelling. The plasma parameters, electron density n_e and electron velocity distribution function, are obtained by means of emission spectroscopy, microphotography and solutions of the Boltzmann equation. The steady state densities of particles in the effluent region are calculated by solving transport equations (thermal conductivity and diffusion) and chemical kinetics equations. The calculated densities of nitrogen atoms are compared with emission spectroscopy measurements at various positions outside the nozzle of the plasma source. The measurements confirm model results. The fluxes of chemically active particles are determined by means of steady state particle densities and known gas flow rate.