adapting by re-engineering products, developing alternative supply sources and delivery methods, addressing pricing and continuing to work closely with our customers and suppliers to navigate through these extraordinary times.
Our balance sheet continues to be very strong, with cash and cash equivalents and marketable securities increasing to $43.2 million at September 30, 2021
With school security a paramount concern to many municipalities, our fully integrated technologies for the school security market continues to remain a top priority especially given the healthy margins those products generate. During, the COVID-19 pandemic we experienced postponements of planned security upgrades but did not suffer a significant number of cancellations. With schools now once again open, we expect to see an uptick in activity in this sector during the coming quarters.
We recently introduced Air Access®, our new cellular based, RMR-generating access control system. These products are designed to help locksmiths, security dealers and integrators to build business and RMR-generating accounts for small and medium-sized businesses, just like our burglar and fire alarm dealers do. While still in the very early stages, we expect this product line to provide the Company the opportunity to generate recurring service revenue from each of our major product lines: alarms & connectivity, locking and access control."
Mr. Soloway concluded, "Our record-setting revenue and profitability in Q1 of fiscal 2022, along with continued strong recurring revenue and associated gross margins, continues to give us tremendous momentum as we head into the upcoming quarters of fiscal 2022. Our fundamental strategy is to provide seamless security solutions for our customers and to continue to grow recurring revenue with both existing and new products. I couldn’t be prouder or more confident in the resiliency of the NAPCO team and how it has responded to the challenges brought on by COVID-19. As markets continue to recover, we are excited for the future prospects for growth as our Company continues its efforts to expand our recurring revenue product offerings into all of our product lines. We remain focused on generating strong revenue growth as well as increased profitability for the balance of fiscal 2022 and beyond.”
Financial Results
Net sales for the quarter increased 34% to a first quarter record of $31.1 million, as compared to $23.2 million for the same period one year ago. Research and development costs for the quarter were $1.9 million or 6% of sales as compared to $1.9 million or 8% of sales for the same quarter a year ago. Selling, general and administrative expenses for the quarter increased 19% to $7.3 million or 24% of net sales, as compared to $6.1 million, or 27% of sales for the same period last year. Operating income for the quarter increased 56% to $4.2 million as compared to $2.7 million for the same period last year. Net income for the quarter increased 224% to a quarterly record of $7.8 million, or $0.42 per diluted share, as compared to $2.3 million, or $0.13 per diluted share for the same period last year.
Adjusted EBITDA* for the quarter increased 170% to $8.6 million, or $0.47 per diluted share, as compared to $3.2 million, or $0.17 per diluted share for the same period last year.
Balance Sheet Summary
At September 30, 2021, the Company had $43.2 million in cash, cash equivalents and marketable securities as compared to $40.2 million as of June 30, 2021. Working capital (defined as current assets less current liabilities) was $81.8 million at September 30, 2021 as compared with working capital of $75.8 million at June 30, 2021. Current ratio (defined as current assets divided by current liabilities) was 6.2:1 at September 30, 2021, and 4.8:1 at June 30, 2021.
Conference Call Information
Management will conduct a conference call at 11 a.m. ET today, November 8,2021. Interested parties may participate in the call by dialing 1-877-407-4018 or for international callers, 1-201-689-8471, about 5-10 minutes prior to the start time of 11 a.m. ET. The conference call will also be available on replay starting at 2 p.m. ET on November 8, 2021, and ending on November 15, 2021 at 11:59 p.m. ET. For the replay, please dial 1-844-512-2921 domestically, or 1-412-317-6671 for international callers, and use the replay access code 13724830.
In addition, the call will be webcast and will be available on the Company's website at www.napcosecurity.com.
About NAPCO Security Technologies, Inc.
NAPCO Security Technologies, Inc., is one of the leading manufacturers and designers of high-tech electronic security devices, wireless recurring communication services for intrusion and fire alarm systems as well as a leading provider of school safety solutions, The Company consists of four Divisions: NAPCO, plus three wholly owned subsidiaries: Alarm Lock, Continental Instruments, and Marks USA. Headquartered in Amityville, New York, its products are installed by tens of thousands of security professionals worldwide in commercial, industrial, institutional, residential and government applications. NAPCO products have earned a reputation for innovation, technical excellence and reliability, positioning the Company for growth in the multi-billion dollar and rapidly