Abstract: The aim of this study was determination of lauramide as a nonionic surfactant in liquid detergent using multivariate calibration. A Partial Least Squares (PLS) algorithm is used to perform the calibration. The concentration of lauramide for experimental calibration matrix was varied between 0.005-0.020 g mL-1. Absorbance data of the calibration standards were taken between 200-600 nm with UV-vis spectrometer. Then absorbance data and concentration were fed to model as input and output, respectively. For achieving the best model parameters of model were evaluated. In other step, first order derivative spectra were considered as input of model and parameters of model were tested. The relative errors in each step were calculated. Relative error less than 2.7% for zero and first derivative spectral data set respectively, were obtained.