Add the cherries, sugar and water to a medium pot on the stove over medium high heat and bring to a boil.
Add the jello powder to a large bowl or serving dish.
Pour the boiling cherry mixture over the jello powder in the bowl or dish, stir to combine until all of the jello powder is dissolved.
Allow to cool on the counter for 15-20 minutes.
Add the coca-cola and pineapple and stir until everything is combined.
Place in the refrigerator to set for 6-8 hours.
The most important step of this recipe is making sure the jello is dissolved in the hot liquid. If the jello does not dissolve in the liquid, your jello salad will not set.
Do NOT use fresh or frozen pineapple in this recipe. An enzyme in the pineapple will cause the jello not to set. Canned pineapple is fine, as the enzyme is broken down in the heating and canning process.
You can make this recipe ahead of time, as it will stay good in the refrigerator for up to 7 days.