Thanks, Michelle. Good morning, everyone, and welcome to Watsco's Fourth Quarter Conference Call. This is Albert Nahmad, President and CEO. With me is Barry Logan, Senior Vice President; and Paul Johnston, Vice President. First, let me give you the first -- the cautionary statement I always do. This conference call has forward-looking statements as defined by the SEC laws and regulations that are made pursuant to the Safe Harbor provisions of these various laws. Ultimate results may differ materially from the forward-looking statements.
Now for the quarter, we delivered strong growth in earnings per share in the face of very difficult sales and earnings comparisons from last year. So I think it's been good execution by our team. Fourth quarter cash flow was a record for any quarter in our company's history, selling margins improved and operating expenses were reduced to produce a 49% increase in operating income and 26% growth in earnings per share. Our balance sheet remains in pristine condition, with net debt near 0 at the year end. For the year, Watsco delivered double-digit earnings per share growth against a very strong 2010 comp. Our team effectively navigated a shift in demand that affected sales mix and a weaker consumer environment.
Highlights of this include Watsco's leadership position in the industry, expanding in 2011. Sales were just shy of $3 billion and operating profit was a record $199 million. Our network expanded by 37 locations in 2011, adding new markets in the Northeast U.S. and Mexico. We also increased our portfolio of commercial products in 2011 and added new locations and other new products. Same-store sales of commercial HVAC equipment were up 18% in 2011 and we expect our expanded footprint to produce additional growth in 2012. Operating margins expanded 90 basis points in 2011 and has increased 270 basis points over the last 2 years, representing substantial progress towards our 10% margin target. Watsco's wide variety of brands and products have brought relative stability to the otherwise volatile market for residential HVAC products. We are well-positioned to compete in all segments, from the value-based models up to the high-tech, high-efficiency units.
Carrier Enterprise, our innovative joint venture with Carrier, ended its second full year with strong earnings growth, and we are very happy about the partnership. And we continue to be impressed by the Carrier Enterprise team on how well they have responded to our entrepreneurial culture.
Now for details on the fourth quarter. Revenues declined 12% on a same-store basis. To remind everyone, organic sales on last year's fourth quarter, that is 2010, increased 17%, with HVAC equipment growth of 23%. Our team did a great job of growing earnings despite the difficult sales comparisons. Same-store gross profit declined 6%, reflecting a 180 basis-point improvement in gross margin on softer sales. SG&A, excluding new locations, decreased 13% or $17 million. Same-store operating income increased 31%, with operating margins also expanding 170 basis points, and diluted earnings per share increased 26% to $0.39.
Moving on to results for the year, same-store sales declined 1%, including a 3% decline in sales of HVAC equipment, a 1% decline in other HVAC products and a 3% increase in sales of commercial refrigeration products. Same-store gross profit improved 2%, with gross margin improving 90 basis points to 24.5%. SG&A, excluding new locations, declined 3%. On a same-store basis, operating income increased 14% versus the 1% decline in sales and operating margins expanded 90 basis points to 6.7%.
Diluted earnings per share increased 10% to $2.74 per share for the year. Now, as to cash flow, Watsco generated a record $120 million of cash flow during the fourth quarter. This performance again demonstrates the safety and cash efficiency of our business in the slower sales environment. Adjusting for one-time payments, cash flow for the year was $148 million or approximately $4.83 per share -- $4.83 per diluted share, well in excess of net income.
We have continued confidence in our ability to generate cash flow and raised our most recent dividend payments to some 9% to $0.62 per share. This marks the 11th consecutive year that we have raised our dividend. Our balance sheet remains in pristine condition, with cash of $16 million and debt of $20 million. We continue to evaluate opportunities to expand our network and can consider almost any sized transaction given the strength of our balance sheet.
As for our outlook, the first quarter is showing softness. This is the slowest time of the year, seasonally, so we will wait until we have a better sense of the selling season to provide a more formal outlook for 2012. As for our long-term outlook, our passion for our fundamentals remains. Our products are a significant component in the movement towards energy efficiency, energy conservation and greener solutions. HVAC systems account for more than half of the energy used in U.S. homes, and 89 million systems are over 10 years old, operating at efficiency levels well below current federal mandates. Replacement of these systems is inevitable and offers us terrific revenue opportunity and meaningful cost savings for consumers. We also continue to build the company. We'll continue to grow our network by opening locations and by making acquisitions. Over the last 10 years, our focus on strategy has produced compounded annual growth rates of 10% for sales, 15% for operating income and 36% for dividends. And our goals remain consistent with our 20-year track record, to provide the best local service, to be a great partner for our suppliers, to innovate with technology and to maintain our conservative, long-term focus on growing a much larger and more valuable company. And we are seeking great talent. To paraphrase a quote from General Colin Powell, "Only by attracting the best people will we accomplish great things." And with that said, Barry, Paul and I will be happy to answer your questions.