In a saucepot over high heat, combine the water, tomato sauce, chili powder, cayenne pepper, and salt. Bring the mix to a boil, stirring occasionally.
Add the long grain rice and butter. Stir to combine and melt the butter.
Reduce the heat to low. Cover the saucepot and let the rice mix simmer, covered, for 18 to 20 minutes.
Remove the saucepot from the heat and stir well.
Serve while hot.
Feel free to experiment with additional ingredients. Spicy Mexican rice is terrific with many additions: black beans, pinto beans, chopped tomato, and cooked peas are just a few ideas to mix into the rice prior to serving.