Union Electric (UEPEM) S-3ASR Automatic shelf registration

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 12.2

Union Electric Company
Computation of Ratios of Earnings to Fixed Charges and Combined
Fixed Charges and Preferred Stock Dividend Requirements
(Thousands of Dollars, Except Ratios)

		3 Months Ended March 31, 2008		3 Months Ended March 31, 2007
Net income from continuing operations		$	64,470	$	33,249
Less—Income from equity investee			10,948		13,591
Add—Taxes based on income			29,112		9,037
Net income before income taxes and income from equity investee			82,634		28,695
Add—fixed charges:
	Interest on long term debt(1)		43,289		50,846
	Estimated interest cost within rental expense		739		558
	Amortization of net debt premium, discount, and expenses		1,456		1,368
Total fixed charges			45,484		52,772
Earnings available for fixed charges			128,118		81,467
Ratio of earnings to fixed charges			2.81		1.54
Earnings required for combined fixed charges and preferred stock dividends:
	Preferred stock dividends		1,485		1,485
	Adjustment to pre-tax basis		671		404
			2,156		1,889
Combined fixed charges and preferred stock dividend requirements		$	47,640	$	54,661
Ratio of earnings to combined fixed charges and preferred stock dividend requirements			2.68		1.49

(1)

Includes FIN 48 interest expense

QuickLinks

Exhibit 12.2

Union Electric Company Computation of Ratios of Earnings to Fixed Charges and Combined Fixed Charges and Preferred Stock Dividend Requirements (Thousands of Dollars, Except Ratios)