To find the missing number in the equation \( 264 \times x = 26.4 \), we can solve for \( x \) by dividing both sides of the equation by \( 264 \):
\[ x = \frac{26.4}{264} \]
Now, perform the division:
\[ x = 0.1 \]
Thus, the missing number is \( \boxed{0.1} \).