The Most hardest languages to learn, for English speakers: 1 ➔ Arabic 2 ➔ Mandarin Chinese 3 ➔ Japanese 4 ➔ Korean 5 ➔ Thai 6 ➔ Vietnamese 7 ➔ Hindi 8 ➔ Russian 9 ➔ Greek 10 ➔ Farsi (Persian) 11 ➔ Turkish 12 ➔ Albanian 13 ➔ Serbian 14 ➔ Bulgarian 15 ➔ Hungarian