EN norms set the methods for determining the ash and volatile content in biomass. These establish the use of a muffle to heat the samples at temperatures of 550 degrees C and 900 degrees C respectively, with a minimum analysis time of 4 h as standard method. The objective of this work was to reduce significantly the analysis times, making very short heating periods using a thermogravimetric scale (TGA), and to apply an equation to the residual weight to obtain the weight of ash, volatiles and fixed carbon in biomass samples. We analyzed the factors: the temperature ramp, atmosphere and airflow in the determination. In this work new validated methods were developed with an analysis time of 10-20 min. (C) 2018 Elsevier Ltd. All rights reserved.