TOMCAT: a MATLAB toolbox for multivariate calibration techniques. We have developed a new user-friendly graphical interface for robust calibration with a collection of m-files, called TOMCAT (TOolbox for Multivariate CAlibration Techniques). The graphical interface and its routines are freely available and programmed in MATLAB 6.5, probably one of the most popular programming environments in the chemometrics community. The graphical interface allows a user to apply the implemented methods in an easy way and it gives a straightforward possibility to visualize the obtained results. Several useful features such as interactive numbering of the displayed objects on a plot, viewing the content of the data, easy transfer of the data between the toolbox and the MATLAB workspace and vice versa, are also implemented. Among the implemented methods there are Principal Component Analysis and its robust variant, Partial Least Squares, Continuum Power Regression, Partial Robust M-Regression, Robust Continuum Regression and Radial Basis Functions Partial Least Squares.