Ensure accurate and reliable measurements in your laboratory and research locations

Our benchtop pH and ORP (Oxidation-Reduction Potential) meters are designed to address a variety of measurement requirements for dependable performance, accuracy, and reproducibility. Identify the best match based on your required features, performance specifications, and budget.

Which benchtop pH and ORP meter is right for you?





  Orion Versa Star Pro pH
Benchtop Meter

(VSTAR10 series)
Orion Star 
A211 pH
Benchtop Meter

(STARA211 series)
Orion Star 
A111 pH
Benchtop Meter

(STARA111 series)
  Premium pH and ORP benchtop meters Advanced pH and ORP benchtop meters Basic pH and ORP benchtop meters
  Versatile, high-performance laboratory measurement system Easy to use, dependable laboratory meters Economical, simplified
laboratory meters
Ideal for
applications in: 
Pharmaceuticals, biotechnology, food and beverage, industrial Water, 
chemical contract testing
pH range –2.000 to 20.000 –2.000 to 20.000  –2.00 to 16.00
pH resolution 0.001 / 0.01 / 0.1 0.001 / 0.01 / 0.1 0.01 / 0.1 
pH calibration points Up to 6 Up to 5 Up to 3 
pH calibration modes Auto buffer recognition with option to edit values Auto buffer recognition with option to edit values Auto buffer recognition or manual buffer entry 
Automatic buffer sets USA/NIST, DIN or custom USA/NIST or DIN USA/NIST or DIN
mV, RmV modes Yes  Yes Yes
ORP mode Yes  Yes
Display type Adjustable color graphic LCD Graphic LCD Fixed segment LCD
Backlit display Yes Yes
Onscreen text prompts Step-by-step calibration and guided setup instructions Step-by-step calibration and guided setup instructions Basic calibration and setup prompts
Keypad Numeric with menu-specific function keys Comprehensive with menu-specific function keys Simple with highlighted measure key
Number of channels 4, customizable with modules 1 1
Included modules 1 x VSTAR-PH
Stirrer probe inputs 2 1
Measure read modes Auto-read, continuous, timed, single-shot Auto-read, continuous, timed Auto-read, continuous
Methods 10 per channel 10
Data log 2000 with date/time 2000 with date/time 50
Calibration log 30 per mode 10
Identification options Electrode ID, sample ID, user ID Sample ID, user ID
Alarms Set point, high/low limit, calibration due High/low limit, calibration due
External device output USB(2), RS232 USB, RS232
Certifications IP-54, CE, TUV 3-in-1, FCC Class A IP-54, CE, TUV 3-in-1, FCC Class A IP-54, CE, TUV 3-in-1, FCC Class A
Power supply Universal, 100–240 VAC, 50-60 Hz Cat. No. STARA-PWR) Universal, 100–240 VAC, 50–60 Hz (Cat. No. 1010003) or 4 AA batteries Universal, 100–240 VAC, 50–60 Hz (Cat. No. 1010003) or 4 AA batteries
  Increase your productivity by adding accessories to your benchtop or portable meter. Meter Accessories ›

Confidence in your pH measurements

The accuracy and reliability of your measurements depend on the instrumentation you use. Learn more about the other products offered as part of this portfolio.

pH and ORP Meters

pH and ORP portable meters

Are you taking samples in the field and bringing them back to the lab? Our portable pH meters are designed to offer simple and accurate pH measurements for your on-the-go measurements. Find the ideal portable meter to complement your laboratory application. 


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pH Electrodes
and Probes

pH and ORP electrodes and probes

Our extensive assortment of quality pH electrodes, sensors, and probes are designed to make your complex measurements routine, reliable, and accurate—in the lab or in the field. They are available in a variety of body materials, body styles, and sample requirements. Find the best electrode for your application.


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Buffers and

buffers and solutions

We offer a variety of pH buffer solutions, pH electrode storage solutions, electrode cleaning solutions, lab buffer kits, and electrode filling solutions for every application. All Thermo Scientific Orion pH lab buffers and solutions are traceable to NIST reference materials. Find the buffers and solutions necessary to complete your measurements.

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Featured pH measurement videos

Calibrating a Thermo Scientific Orion Star A series pH benchtop meter

Measuring pH in drinking water using the Thermo Scientific Orion Versa Star Pro benchtop meter


Knowledge Base: Certificates of Analysis and SDS for Orion, ROSS, AQUAfast, AquaMate, and AquaSensors products.

Orion Meters Software and Upgrades
Thermo Scientific Orion benchtop and portable meters are designed to help deliver accurate, consistent results, day after day. Boost productivity by upgrading your software today.

Find your software