Caffenol Recipes that are proven to work can be found here. If not stated differently, the temperature of the solution should be 20 degrees Celsius or 68 degrees Fahrenheit. For all other temperatures, please adjust the developing time accordingly. If you have never used caffenol before, I suggest that you start with films that are proven to deliver decent results, for example the 400 ISO films Ilford HP5 Plus, or Kodak TMAX 400. Slow films that work are Ilford FP4 (ISO 125) and Ilford PanF (ISO 50). Developing times and links to example pictures can be found in the Film Development Chart.
http://www.caffenol.org/recipes/