This script modifies the reaction rate data in a Webnucleo network file so that the rates are multiplied by a constant factor at all temperatures. For user-defined rates, the user must modify the script to accommodate his or her own rate formulation. To use, first download the file by typing **curl -o modify_xml_rates_by_constant_factor.py -J -L https://osf.io/j9gfm/download** Use the script on a Webnucleo network XML file (in this example, called net_full.xml). This will be a network (nuclides plus reactions) XML file. Any such XML file will do, but to obtain an example, type **curl -o net_full.xml -J -L https://osf.io/9xmz5/download** Modify the valid reactions (chosen by XPath expressions) and dump the data to a new network file called new_net.xml. For example, type **python modify_xml_rates_by_constant_factor.py net_full.xml new_net.xml --nuc_xpath "[(a = 1) or (z = 40)]" --reac_xpath "[reactant = 'n' and product = 'gamma']" --mod_factor 10** This command will increase all *(n, gamma)* reactions for isotopes of Zr by a factor of 10 at all temperatures when computed from the *new_net.xml* file.