In this research, the theme for employing a simple and sensitive method is to employ a new Schiff base ligand (N’-(4- (dimethyl amino) benzylidene)-3, 5-dinitrobenzohydrazide) to estimate Ni (II) to form orange complex (N-(4-(dimethyl amino) benzylidene)-3, 5-dinitrobenzohydrazide nickel (II) chloride) in acid medium (hydrochloric acid), it gives an absorption peak at the wavelength 485 nm. The preferred conditions were studied to form the complex and obtain the highest absorbance including concentration of Schiff base ligand, the best medium for complex formation, effects of addition sequence on complex formation, the effect of temperature on the absorbance of the complex formed, and the setting time of the formed complex. The obtained results show the extent of the scatter plot 0.03–6 ppm and linear range 0.03–5 ppm. The relative standard deviation RSD % was calculated and the ratio was less than 4% for n = 8, the percentage recovery was calculated and the results were within acceptable percentages, correlation coefficient equal to 0.99995 was obtained, while the estimation coefficient was equal to 0.9999 and percentage capital R-squared explained variation as a percentage/total variation equal to 99.99. The method is considered one of the successful methods for estimation of Ni (II) in its aqueous solution also in different specimens in which it is found at the lowest cost, and by using a newly prepared Schiff base ligand and for the first time it is used in the estimation of Ni (II).
