Nanocrystalline Co-P coatings prepared by pulse current electrodeposition have currently received considerable attraction. In this work nanocrystalline Co-P coating was produced by DC Electrodeposition. The effect of current density in range of 150-250 mA/cm 2 on characteristics of coating was investigated. It was found that by increasing current density the phosphorous content of coating reduced from 2wt% to 1wt%. Also the grain size of coating increased from 10nm to 16nm as current density increased from 150 to 250 mA/cm 2 . However the morphology, texture as well as corrosion behavior (in 3.5% NaCl) of coating did not affect by current density. Moreover the effect of annealing on characteristics of nanocrystalline Co 1-2wt% and amorphous Co 9-11Wt% was studied. The results showed that after annealing the grain size and texture of nanocrystalline coating remained unchanged whereas the amorphous coating transformed to the nanocrystalline structure. It was found that the relative intensity basal plane for coating obtained from crystallization of amorphous coating is significantly higher than that for nanocrystalline coating. Moreover the hardness of both coating increased after annealing as a result of formation of Co 2 P and CoP precipitates. This increase was higher for amorphous coating due to its high phosphorous content and therefore higher fraction of Co 2 P and CoP precipitates.Tafel polarization tests of the coatings in 0.1M H 2 SO 4 solution revealed that the amorphous coating has better corrosion resistance compared to nanocrystalline one. Corrosion resistance of both coatings in this solution decreased after annealing. Neither nanocrystalline nor amorphous coatings did not passivate in 3.5% NaCl or 0.1M H 2 SO 4 solutions but both of coatings showed an active-passive behavior in 10% NaOH solution. Passive current density of amorphous coating was higher that for than nanocrystalline coating. In addition the passive current density of amorphous coating decreased remarkably after annealing but in the case of nanocrystalline coating this decrease in passive current density was too smaller. Also the results showed that the adhesion of the coatings to the substrates prepared by electropolishing is weak but by substrate activation in 25% HCl, adequate adhesion can be achieved. Cross section study of the coatings revealed that there is no crack and porosity in the structure.