Although /ɔːlˈðəʊ/ (US /ɔːlˈðoʊ/). One word, no hyphen or doubling. Example: Although it rained, we walked on.
Sound-to-spelling: the final gh is silent, th is voiced /ð/, and ou maps to /ɔː/ here, not /aʊ/ as in out. Watch for althought and allthough; neither is standard.
The spelling although /ɔːlˈðəʊ/ (US /ɔːlˈðoʊ/) is one word, no hyphen or doubling. It fits naturally in a sentence: Although the train was late, we arrived on time.
A second example shows the same spelling in context: Although she smiled, she said nothing. In both cases the written form is simply although, never all though in this slot.
Sound-to-spelling: the final gh is silent, th is voiced /ð/, and ou maps to /ɔː/ here, not /aʊ/ as in out. That /ɔː/ comes from ou as in bought, which is why the misspellings happen: althought adds a t that no sound in the word justifies, and allthough doubles the l even though this vowel comes from ou, not from the doubled ll in all. Neither spelling is standard.