Every time I try to mix a large amount of cocoa powder (ie. enough for a cup of hot chocolate) into a large amount of hot water (ie. a cup full), I end up with a significant amount of "cocoa sludge" where the powder doesn't dissolve properly and turns into a big, clumpy mess.

It doesn't matter if I pour the cocoa in first and pour hot water on top of it, or if I pour cocoa powder into a cup full of hot water. It doesn't matter if I stir or not (stirring can even make it worse; cocoa sludge sticks surprisingly well to plastic spoons!) or even if I pour the cocoa powder in very slowly, a little bit at a time, to give it time to dissolve. I still end up with a bunch of cocoa sludge no matter what I do. Often, stirring can even make a protective layer of cocoa sludge form in a bubble around pristine cocoa powder, which then needs to be broken open so it can dissolve.

Does anyone know any good tricks to making all of the cocoa powder dissolve properly and emerging out the other side with a nice, smooth cup of hot chocolate?

5 Answers 5


You can try this experiment: add the cocoa, add a small amount of hot water (just a few tablespoons should do), and stir thoroughly. Completely dissolve the cocoa in the small amount of hot water. Then add the rest of the hot water, and stir just a few times. That should give you better results.

  • 3
    +1 This is basically the instructions that are on the side of many jars of cocoa.
    – Lefty
    Jun 16, 2017 at 7:05
  • @Lefty That's funny! Makes sense. Jun 16, 2017 at 16:23
  • 2
    It's a similar technique that's used for mixing cornflour with water for thickening sauces. Chefs refer to it as "slaking" the powder before adding the hot water.
    – Lefty
    Jun 18, 2017 at 20:45
  • 1
    @Lefty yep, that's how my mom showed me. Hot water for oily powders like cocoa but cold water for starchy powders as heat would start the gelatinization too early and you'd end up with a big undisolvable glob.
    – Flint
    Jul 22, 2017 at 13:58

Or use the old recipe, the one my grandmother used.

Use one spoon real cocoa (not the mix most people now call cocoa,) one spoon sugar, one spoon cold milk or liquid coffee creamer, mix well. This will give you a very thick (and nice tasting) chocolate mix.

Now add milk that is almost boiling.

Add the milk bit by bit, so you can stir the mix into the milk and let it desolve.


It's all about the heat. When the lipids and sugar come into contact with the bottom or sides of the pot, they go through a slight burn process and then oxidize. That gives you the undesirable burned odor and flavor.

Get a candy thermometer (very inexpensive at big-box stores, less than $5), place it in the pot and stir slowly over low heat with a small whisk. Allow the temperature rise to between 160° and 180° F. which will reliably reduce all the sugar and chocolate but prevent burning. Then turn off the heat. The process will take about 5 minutes and require you to stay with the pot, but you get great hot chocolate this way.


When mixing a fine powder, which is basically a flour like substance, with a hot liquid, this is usually the problem.

The solution is to mix the powder with a bit of cold liquid, until the consistency is like a thick batter, then add the hot liquid.

This technique is commonly used to thicken a soup by adding the flour/cold water mix directly into the boiling soup.

  • Flour and soup? That's a bit off-topic. The question was about Hot Chocolate. Also, "fine powder" might be a better generic description than "flour like."
    – Stan
    Jul 21, 2017 at 23:10

Based on my experience, hotter water is the biggest help.

If your water is close to boiling, and your cocoa isn't too stale, it should dissolve almost instantly. For whatever it's worth, I've always put the cocoa in the cup, added the hot water (or coffee -- I like it better made with coffee), and then stirred.

If you're using tap water in an office lunch room, it's very unlikely to be above 130 F, which is at least forty degrees (F) too cool to make cocoa well; try putting it in a microwave for about 40-60 seconds to warm it further.

  • I'm getting the hot water out of a valve on the side of the coffee machine. It's significantly hotter than tap water, but not "close to boiling." Jun 15, 2017 at 16:43
  • That water might still not be hot enough (many office coffee urns make horrible coffee, even if the correct amount of grounds is used, because they're just poorly designed). Try giving it 30 seconds in the microwave?
    – Zeiss Ikon
    Jun 15, 2017 at 16:49

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