*Note please refer to specific canning instructions on water bath canning either online or in a book. I also have a link in the notes section for my post that goes into more specific detail on water bath canning.
Combine lemons and water in medium non reactive pot. Bring to a boil over high heat, cover and reduce heat. Boil gently for 25 minutes, stirring occasionally.
Add mangoes to saucepan. Bring to a boil over high heat, stirring constantly. Reduce heat, cover and boil gently for 20 minutes, stirring occasionally.
Stir in sugar. Return to a boil and boil, rapidly, uncovered until mixture will form a gel (use gel test method of your choice) about 15 minutes, stirring frequently.
Ladle in sterilized jars, wipe rims, place lids, and process in a water bath for 10 minutes.
Notes
Makes about 3 cups. For more complete instructions on water bath canning - follow my link - Water Bath Canning or use a canning book.