In this research, the effects of annealing and ageing processes on mechanical properties of cast nickel aluminum bronze were studied. In addition, since this alloy has marine applications, corrosion behavior in sodium chloride solution and sea water (prepared from Persian Gulf) were investigated. For this purpose, the mechanical properties of nickel aluminum bronze specimens before and after heat treatment were tested by Vickers hardness, tensile and bending fatigue and corrosion behavior was studied through electrochemical techniques (potentiodynamic polarization and cyclic polarization). Observation of microstructure and fracture surfaces after tensile and fatigue tests showed that the alloy had pores in the structure, caused by casting shrinkage, that were disadvantageous to alloy fracture strength. The effect of porosity on the strength of as-cast and aged nickel aluminum bronze was evaluated by experimental data and application of a correction model; an effective area was defined as the total cross sectional area minus the projected area of porosity obtained by fractography. Then, fatigue and tensile strengths of the specimens were calculated based on the effective area; the effective strength of the alloy proved much higher than the strength obtained in fatigue and tensile tests. In addition, effective strength followed the same trend of variations as hardness in the ageing process. It was concluded that effective strength could be an appropriate reference value when considering the mechanical properties of such casting alloys and to study the role of age hardening treatment. Ageing process improved tensile strength and fatigue strength by 20% and 60%, respectively. Results of corrosion tests revealed selective corrosion and pitting as the dominant mechanisms in this alloy. Potentiodynamic polarization experiments proved that annealing enhanced the pitting potential. However, annealing process at 670°C reduced the chance of forming local galvanic cells, which might exist between different phases and improved the corrosion resistance of the alloy. The as-cast and annealed specimens displayed the least and the highest corrosion resistance, respectively; the aged specimens indicated a moderate corrosion behavior. Keywords: nickel aluminum bronze, age hardening, corrosion, fatigue strength