This dataset accompanies the corresponding article in Communications Earth and Environment. It contains the key assumptions used in the energy system modelling with the Swiss TIMES energy systems model (STEM) for assessing net-zero carbon dioxide emissions scenarios for Switzerland. In addition, contains extensive results from STEM for each one of the core scenarios and variants assessed in the study. The following files are contained in this repository: Supplementary Data 1: This is the EXCEL file "Supplementary_Information_Assumptions.xslx" which contains key assumptions of the long-term scenarios assessed with STEM. These include among others: the major energy and climate policies in each scenario, the economic and demographic assumptions, key drivers for the residential energy demand (e.g., floor reference area or appliances), key drivers for the energy demand in the services sectors (e.g., Gross Value Added or floor area), key drivers for the energy demand in industry (e.g., production index or Gross Value Added), mobility demands, energy import prices, hourly electricity import prices, net transfer capacities, domestic sustainable renewable resource potentials, energy supply and demand technologies costs and efficiencies Supplementary Data 2: This is the EXCEL file "Supplementary_Information_Results.xlsx" which contains energy balances from the baseline and the net-zero CO2 emissions scenarios. The results for each scenario are: domestic production by fuel, net imports by fuel, primary energy consumption by fuel, input to conversion sectors by fuel, electricity supply and capacities by fuel, district heating supply by fuel, final energy consumption by fuel and sector, CO2 emissions by source, energy system costs, and indicators such as energy consumption per capita, energy intensity of GDP, CO2 emissions per capita and CO2 intensity of GDP. Supplementary Data 3: The ZIP file "Source_code_and_data_for_charts.zip" contains source codes and data for reproducing the figures in the manuscript.